https://github.com/hekota updated
https://github.com/llvm/llvm-project/pull/92207
>From 3df0ba0fd2171a0115427bc6ba5e3f8e84831747 Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Tue, 14 May 2024 19:06:59 -0700
Subject: [PATCH 1/8] HLSL Availability Diagnostics Design Document - initial
commit
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 50 +++++++++++++++++++++
clang/docs/HLSL/HLSLDocs.rst | 1 +
2 files changed, 51 insertions(+)
create mode 100644 clang/docs/HLSL/AvailabilityDiagnostics.rst
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
new file mode 100644
index 0000000000000..218047495e6b9
--- /dev/null
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -0,0 +1,50 @@
+=============================
+HLSL Availability Diagnostics
+=============================
+
+.. contents::
+ :local:
+
+Introduction
+============
+
+HLSL availability diagnostics emits errors or warning when unavailable shader
APIs are used. Unavailable shader APIs are APIs that are exposed in HLSL code
but are not available in the target shader stage or shader model version.
+
+There are three modes of HLSL availability diagnostic:
+1. **Default mode** - compiler emits an error when an unavailable shader API
is found in a code that is reachable from the shader entry point function or
from an exported library function (when compiling a shader library)
+2. **Relaxed mode** - same as default mode except the compiler emits a
warning. This mode is enabled by ``-Wno-error=hlsl-availability``.
+3. **Strict mode** - compiler emits an error when when an unavailable API is
found in parsed code regardless of whether it can be reached from the shader
entry point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
+
+Implementation Details
+======================
+
+Environment Parameter
+---------------------
+
+In order to encode API availability based on the shader model version and
shader model stage a new ``environment`` parameter was added to the existing
Clang ``availability`` attribute.
+
+The values allowed for this parameter are a subset of values allowed as the
``llvm::Triple`` environment component. If the environment parameters is
present, the declared availability attribute applies only to targets with the
same platform and environment.
+
+Default and Relaxed Diagnostic Modes
+------------------------------------
+
+This mode is implemeted in ``DiagnoseHLSLAvailability`` class in
``SemaHLSL.cpp`` and it is invoked after the whole translation unit is parsed
(from ``Sema::ActOnEndOfTranslationUnit``). The implementation iterates over
all shader entry points and exported library functions in the translation unit
and performs an AST traversal of each function body.
+
+When a reference to another function is found and it has a body, the AST of
the referenced function is also scanned. This chain of AST traversals will
reach all of the code that is reachable from the initial shader entry point or
exported library function.
+
+All shader APIs have an availability attribute that specifies the shader model
version (and environment, if applicable) when this API was first
introduced.When a reference to a function without a definition is found and it
has an availability attribute, the version of the attribute is checked against
the target shader model version and shader stage (if shader stage context is
known), and an appropriate diagnostic is generated as needed.
+
+All shader entry functions have ``HLSLShaderAttr`` attribute that specifies
what type of shader this function represents. However, for exported library
functions the target shader stage is unknown, so in this case the HLSL API
availability will be only checked against the shader model version.
+
+A list of functions that were already scanned is kept in order to avoid
duplicate scans and diagnostics (see
``DiagnoseHLSLAvailability::ScannedDecls``). It might happen that a shader
library has multiple shader entry points for different shader stages that all
call into the same shared function. It is therefore important to record not
just that a function has been scanned, but also in which shader stage context.
This is done by using ``llvm::DenseMap`` that maps ``FunctionDecl *`` to a
``unsigned`` bitmap that represents a set of shader stages (or environments)
the function has been scanned for. The ``N``'th bit in the set is set if the
function has been scanned in shader environment whose
``HLSLShaderAttr::ShaderType`` integer value equals ``N``.
+
+The emitted diagnostic messages belong to ``hlsl-availability`` diagnostic
group and are reported as errors by default. With
``-Wno-error=hlsl-availability`` flang they become warning, making it relaxed
HLSL diagnostics mode.
+
+Strict Diagnostic Mode
+----------------------
+
+When strict HLSL availability diagnostic mode is enabled the compiler must
report all HLSL API availability issues regardless of code reachability. The
implementation of this mode takes advantage of an existing diagnostic scan in
``DiagnoseUnguardedAvailability`` class which is already traversing AST of each
function as soon as the function body has been parsed.
+
+If the compilation target is a shader library, only availability based on
shader model version can be diagnosed during this scan. To diagnose
availability based on shader stage, teh compiler will also run the AST
traversals implementated in ``DiagnoseHLSLAvailability`` at the end of the
translation unit as described in previous chapter.
+
+As a result, availability based on specific shader stage will only be
diagnosed in code that is reachable from a shader entry point or library export
function. It also means that function bodies might be scanned multiple time.
When that happens, care should be taken not to produce duplicated diagnostics.
diff --git a/clang/docs/HLSL/HLSLDocs.rst b/clang/docs/HLSL/HLSLDocs.rst
index 97b2425f013b3..1e50a66d984b5 100644
--- a/clang/docs/HLSL/HLSLDocs.rst
+++ b/clang/docs/HLSL/HLSLDocs.rst
@@ -16,3 +16,4 @@ HLSL Design and Implementation
ResourceTypes
EntryFunctions
FunctionCalls
+ AvailabilityDiagnostics
>From 2b5b0cd183e792003cdb93d339b325dd47ab3663 Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Tue, 14 May 2024 19:24:53 -0700
Subject: [PATCH 2/8] Fix list formatting and add more details for the strict
mode
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 218047495e6b9..04ac3bb565706 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -11,9 +11,12 @@ Introduction
HLSL availability diagnostics emits errors or warning when unavailable shader
APIs are used. Unavailable shader APIs are APIs that are exposed in HLSL code
but are not available in the target shader stage or shader model version.
There are three modes of HLSL availability diagnostic:
-1. **Default mode** - compiler emits an error when an unavailable shader API
is found in a code that is reachable from the shader entry point function or
from an exported library function (when compiling a shader library)
-2. **Relaxed mode** - same as default mode except the compiler emits a
warning. This mode is enabled by ``-Wno-error=hlsl-availability``.
-3. **Strict mode** - compiler emits an error when when an unavailable API is
found in parsed code regardless of whether it can be reached from the shader
entry point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
+
+#. **Default mode** - compiler emits an error when an unavailable shader API
is found in a code that is reachable from the shader entry point function or
from an exported library function (when compiling a shader library)
+
+#. **Relaxed mode** - same as default mode except the compiler emits a
warning. This mode is enabled by ``-Wno-error=hlsl-availability``.
+
+#. **Strict mode** - compiler emits an error when when an unavailable API is
found in parsed code regardless of whether it can be reached from the shader
entry point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
Implementation Details
======================
@@ -43,8 +46,8 @@ The emitted diagnostic messages belong to
``hlsl-availability`` diagnostic group
Strict Diagnostic Mode
----------------------
-When strict HLSL availability diagnostic mode is enabled the compiler must
report all HLSL API availability issues regardless of code reachability. The
implementation of this mode takes advantage of an existing diagnostic scan in
``DiagnoseUnguardedAvailability`` class which is already traversing AST of each
function as soon as the function body has been parsed.
+When strict HLSL availability diagnostic mode is enabled the compiler must
report all HLSL API availability issues regardless of code reachability. The
implementation of this mode takes advantage of an existing diagnostic scan in
``DiagnoseUnguardedAvailability`` class which is already traversing AST of each
function as soon as the function body has been parsed. For HLSL, this pass was
only slightly modified, such as making sure diagnostic messages are in the
```hlsl-availability`` group and that availability checks based on shader stage
are not included if the shader stage context is unknown.
-If the compilation target is a shader library, only availability based on
shader model version can be diagnosed during this scan. To diagnose
availability based on shader stage, teh compiler will also run the AST
traversals implementated in ``DiagnoseHLSLAvailability`` at the end of the
translation unit as described in previous chapter.
+If the compilation target is a shader library, only availability based on
shader model version can be diagnosed during this scan. To diagnose
availability based on shader stage, the compiler needs to run the AST
traversals implementated in ``DiagnoseHLSLAvailability`` at the end of the
translation unit as described above.
As a result, availability based on specific shader stage will only be
diagnosed in code that is reachable from a shader entry point or library export
function. It also means that function bodies might be scanned multiple time.
When that happens, care should be taken not to produce duplicated diagnostics.
>From 699c4c1eaf8f4c736eb94a87ed230f91c0dea7c0 Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Wed, 15 May 2024 14:26:48 -0700
Subject: [PATCH 3/8] Code review feedback
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 04ac3bb565706..8db255300d212 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -12,11 +12,11 @@ HLSL availability diagnostics emits errors or warning when
unavailable shader AP
There are three modes of HLSL availability diagnostic:
-#. **Default mode** - compiler emits an error when an unavailable shader API
is found in a code that is reachable from the shader entry point function or
from an exported library function (when compiling a shader library)
+#. **Default mode** - compiler emits an error when an unavailable API is found
in a code that is reachable from the shader entry point function or from an
exported library function (when compiling a shader library)
#. **Relaxed mode** - same as default mode except the compiler emits a
warning. This mode is enabled by ``-Wno-error=hlsl-availability``.
-#. **Strict mode** - compiler emits an error when when an unavailable API is
found in parsed code regardless of whether it can be reached from the shader
entry point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
+#. **Strict mode** - compiler emits an error when an unavailable API is found
in parsed code regardless of whether it can be reached from the shader entry
point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
Implementation Details
======================
@@ -31,17 +31,17 @@ The values allowed for this parameter are a subset of
values allowed as the ``ll
Default and Relaxed Diagnostic Modes
------------------------------------
-This mode is implemeted in ``DiagnoseHLSLAvailability`` class in
``SemaHLSL.cpp`` and it is invoked after the whole translation unit is parsed
(from ``Sema::ActOnEndOfTranslationUnit``). The implementation iterates over
all shader entry points and exported library functions in the translation unit
and performs an AST traversal of each function body.
+This mode is implemented in ``DiagnoseHLSLAvailability`` class in
``SemaHLSL.cpp`` and it is invoked after the whole translation unit is parsed
(from ``Sema::ActOnEndOfTranslationUnit``). The implementation iterates over
all shader entry points and exported library functions in the translation unit
and performs an AST traversal of each function body.
When a reference to another function is found and it has a body, the AST of
the referenced function is also scanned. This chain of AST traversals will
reach all of the code that is reachable from the initial shader entry point or
exported library function.
All shader APIs have an availability attribute that specifies the shader model
version (and environment, if applicable) when this API was first
introduced.When a reference to a function without a definition is found and it
has an availability attribute, the version of the attribute is checked against
the target shader model version and shader stage (if shader stage context is
known), and an appropriate diagnostic is generated as needed.
-All shader entry functions have ``HLSLShaderAttr`` attribute that specifies
what type of shader this function represents. However, for exported library
functions the target shader stage is unknown, so in this case the HLSL API
availability will be only checked against the shader model version.
+All shader entry functions have ``HLSLShaderAttr`` attribute that specifies
what type of shader this function represents. However, for exported library
functions the target shader stage is unknown, so in this case the HLSL API
availability will be only checked against the shader model version. It means
that for exported library functions the diagnostic of APIs with availability
specific to shader stage will be deferred until DXIL linking time.
A list of functions that were already scanned is kept in order to avoid
duplicate scans and diagnostics (see
``DiagnoseHLSLAvailability::ScannedDecls``). It might happen that a shader
library has multiple shader entry points for different shader stages that all
call into the same shared function. It is therefore important to record not
just that a function has been scanned, but also in which shader stage context.
This is done by using ``llvm::DenseMap`` that maps ``FunctionDecl *`` to a
``unsigned`` bitmap that represents a set of shader stages (or environments)
the function has been scanned for. The ``N``'th bit in the set is set if the
function has been scanned in shader environment whose
``HLSLShaderAttr::ShaderType`` integer value equals ``N``.
-The emitted diagnostic messages belong to ``hlsl-availability`` diagnostic
group and are reported as errors by default. With
``-Wno-error=hlsl-availability`` flang they become warning, making it relaxed
HLSL diagnostics mode.
+The emitted diagnostic messages belong to ``hlsl-availability`` diagnostic
group and are reported as errors by default. With
``-Wno-error=hlsl-availability`` flag they become warning, making it relaxed
HLSL diagnostics mode.
Strict Diagnostic Mode
----------------------
>From 837b61732eb7d2dbbce3fc133b99acf632208b5c Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Wed, 15 May 2024 14:35:28 -0700
Subject: [PATCH 4/8] Update clang/docs/HLSL/AvailabilityDiagnostics.rst
Co-authored-by: Xiang Li <python3k...@outlook.com>
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 8db255300d212..28c0f5ee94417 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -46,7 +46,7 @@ The emitted diagnostic messages belong to
``hlsl-availability`` diagnostic group
Strict Diagnostic Mode
----------------------
-When strict HLSL availability diagnostic mode is enabled the compiler must
report all HLSL API availability issues regardless of code reachability. The
implementation of this mode takes advantage of an existing diagnostic scan in
``DiagnoseUnguardedAvailability`` class which is already traversing AST of each
function as soon as the function body has been parsed. For HLSL, this pass was
only slightly modified, such as making sure diagnostic messages are in the
```hlsl-availability`` group and that availability checks based on shader stage
are not included if the shader stage context is unknown.
+When strict HLSL availability diagnostic mode is enabled the compiler must
report all HLSL API availability issues regardless of code reachability. The
implementation of this mode takes advantage of an existing diagnostic scan in
``DiagnoseUnguardedAvailability`` class which is already traversing AST of each
function as soon as the function body has been parsed. For HLSL, this pass was
only slightly modified, such as making sure diagnostic messages are in the
``hlsl-availability`` group and that availability checks based on shader stage
are not included if the shader stage context is unknown.
If the compilation target is a shader library, only availability based on
shader model version can be diagnosed during this scan. To diagnose
availability based on shader stage, the compiler needs to run the AST
traversals implementated in ``DiagnoseHLSLAvailability`` at the end of the
translation unit as described above.
>From 4234d26849ee65f4e412a2026b651f327180c3b9 Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Thu, 16 May 2024 18:42:39 -0700
Subject: [PATCH 5/8] Add examples, add note about constructing call graph
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 87 ++++++++++++++++++++-
1 file changed, 86 insertions(+), 1 deletion(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 8db255300d212..c82cf2437ef5b 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -33,7 +33,9 @@ Default and Relaxed Diagnostic Modes
This mode is implemented in ``DiagnoseHLSLAvailability`` class in
``SemaHLSL.cpp`` and it is invoked after the whole translation unit is parsed
(from ``Sema::ActOnEndOfTranslationUnit``). The implementation iterates over
all shader entry points and exported library functions in the translation unit
and performs an AST traversal of each function body.
-When a reference to another function is found and it has a body, the AST of
the referenced function is also scanned. This chain of AST traversals will
reach all of the code that is reachable from the initial shader entry point or
exported library function.
+When a reference to another function or member method is found
(``DeclRefExpr`` or ``MemberExpr``) and it has a body, the AST of the
referenced function is also scanned. This chain of AST traversals will reach
all of the code that is reachable from the initial shader entry point or
exported library function.
+
+Another approach would be to construct a call graph by traversing the AST and
recording caller and callee for each ``CallExpr``. The availability diagnostics
would then run on the call graph. Since Clang currently does not build any call
graph during compilation, this seems like an unnecessary step. Traversing all
function references (``DeclRefExpr`` or ``MemberExpr``) works just as well, and
can be easily extended to support availability diagnostic of classes and other
AST nodes.
All shader APIs have an availability attribute that specifies the shader model
version (and environment, if applicable) when this API was first
introduced.When a reference to a function without a definition is found and it
has an availability attribute, the version of the attribute is checked against
the target shader model version and shader stage (if shader stage context is
known), and an appropriate diagnostic is generated as needed.
@@ -51,3 +53,86 @@ When strict HLSL availability diagnostic mode is enabled the
compiler must repor
If the compilation target is a shader library, only availability based on
shader model version can be diagnosed during this scan. To diagnose
availability based on shader stage, the compiler needs to run the AST
traversals implementated in ``DiagnoseHLSLAvailability`` at the end of the
translation unit as described above.
As a result, availability based on specific shader stage will only be
diagnosed in code that is reachable from a shader entry point or library export
function. It also means that function bodies might be scanned multiple time.
When that happens, care should be taken not to produce duplicated diagnostics.
+
+========
+Examples
+========
+
+.. note::
+ ``WaveActiveCountBits`` function became available in shader model 6.0.
+
+ ``WaveMultiPrefixSum`` function became available in shader model 6.5.
+
+ The availability of ``ddx`` function depends on a shader stage. It is
available for pixel shaders in shader model 2.1 and higher, for compute, mesh
and amplification shaders in shader model 6.6 and higher. For any other shader
stages it is not available.
+
+Compute shader example
+----------------------
+
+.. code-block:: c++
+
+ float unusedFunction(float f) {
+ return ddx(f);
+ }
+
+ [numthreads(4, 4, 1)]
+ void main(uint3 threadId : SV_DispatchThreadId) {
+ float f1 = ddx(threadId.x);
+ float f2 = WaveActiveCountBits(threadId.y == 1.0);
+ }
+
+When compiled as compute shader version 5.0, clang will emit the following
error by default:
+
+.. code-block: none
+ <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
+ <>:8:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+
+With relaxed diagnostic mode this errors will become warnings.
+
+With strict deagnostic mode, in addition to the 2 errors above clang will also
emit error for the ``ddx`` call in ``unusedFunction``.:
+
+.. code-block: none
+ <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+ <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+ <>:7:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+
+Shader library example
+----------------------
+
+.. code-block:: c++
+ float myFunction(float f) {
+ return ddx(f);
+ }
+
+ float unusedFunction(float f) {
+ return WaveMultiPrefixSum(f, 1.0);
+ }
+
+ [shader("compute")]
+ [numthreads(4, 4, 1)]
+ void main(uint3 threadId : SV_DispatchThreadId) {
+ float f = 3;
+ float e = myFunction(f);
+ }
+
+ [shader("pixel")]
+ void main() {
+ float f = 3;
+ float e = myFunction(f);
+ }
+
+When compiled as shader library version 6.4, clang will emit the following
error by default:
+
+.. code-block: none
+ <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+
+With relaxed diagnostic mode this errors will become warnings.
+
+With strict diagnostic mode clang will also emit errors for availability
issues in code that is not used by any of the entry points:
+
+.. code-block: none
+
+ <>2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
+
+ <>:6:9: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+
+Note that ``myFunction`` is reachable from both pixel and compute shader entry
points is therefore scanned twice - once for each context. The diagnostic is
emitted only for the compute shader context.
>From 40401d7e1b2c97a34a4bfdc4da973ffbd063378f Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Thu, 16 May 2024 19:04:27 -0700
Subject: [PATCH 6/8] Update wording and code blocks
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 93 ++++++++++-----------
1 file changed, 44 insertions(+), 49 deletions(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 6440309530e4d..710fc3aa92b8d 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -58,81 +58,76 @@ As a result, availability based on specific shader stage
will only be diagnosed
Examples
========
-.. note::
- ``WaveActiveCountBits`` function became available in shader model 6.0.
-
- ``WaveMultiPrefixSum`` function became available in shader model 6.5.
+**Note**
+For the example below, the ``WaveActiveCountBits`` API function became
available in shader model 6.0 and ``WaveMultiPrefixSum`` in shader model 6.5.
- The availability of ``ddx`` function depends on a shader stage. It is
available for pixel shaders in shader model 2.1 and higher, for compute, mesh
and amplification shaders in shader model 6.6 and higher. For any other shader
stages it is not available.
+The availability of ``ddx`` function depends on a shader stage. It is
available for pixel shaders in shader model 2.1 and higher, for compute, mesh
and amplification shaders in shader model 6.6 and higher. For any other shader
stages it is not available.
Compute shader example
----------------------
.. code-block:: c++
+ float unusedFunction(float f) {
+ return ddx(f);
+ }
- float unusedFunction(float f) {
- return ddx(f);
- }
-
- [numthreads(4, 4, 1)]
- void main(uint3 threadId : SV_DispatchThreadId) {
- float f1 = ddx(threadId.x);
- float f2 = WaveActiveCountBits(threadId.y == 1.0);
- }
+ [numthreads(4, 4, 1)]
+ void main(uint3 threadId : SV_DispatchThreadId) {
+ float f1 = ddx(threadId.x);
+ float f2 = WaveActiveCountBits(threadId.y == 1.0);
+ }
When compiled as compute shader version 5.0, clang will emit the following
error by default:
-.. code-block: none
- <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
- <>:8:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+.. code-block:: console
+ <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
+ <>:8:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
With relaxed diagnostic mode this errors will become warnings.
-With strict deagnostic mode, in addition to the 2 errors above clang will also
emit error for the ``ddx`` call in ``unusedFunction``.:
+With strict diagnostic mode, in addition to the 2 errors above clang will also
emit error for the ``ddx`` call in ``unusedFunction``.:
-.. code-block: none
- <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
- <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
- <>:7:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+.. code-block:: console
+ <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+ <>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+ <>:7:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
Shader library example
----------------------
.. code-block:: c++
- float myFunction(float f) {
- return ddx(f);
- }
-
- float unusedFunction(float f) {
- return WaveMultiPrefixSum(f, 1.0);
- }
-
- [shader("compute")]
- [numthreads(4, 4, 1)]
- void main(uint3 threadId : SV_DispatchThreadId) {
- float f = 3;
- float e = myFunction(f);
- }
-
- [shader("pixel")]
- void main() {
- float f = 3;
- float e = myFunction(f);
- }
+ float myFunction(float f) {
+ return ddx(f);
+ }
+
+ float unusedFunction(float f) {
+ return WaveMultiPrefixSum(f, 1.0);
+ }
+
+ [shader("compute")]
+ [numthreads(4, 4, 1)]
+ void main(uint3 threadId : SV_DispatchThreadId) {
+ float f = 3;
+ float e = myFunction(f);
+ }
+
+ [shader("pixel")]
+ void main() {
+ float f = 3;
+ float e = myFunction(f);
+ }
When compiled as shader library version 6.4, clang will emit the following
error by default:
-.. code-block: none
- <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
+.. code-block:: console
+ <>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
With relaxed diagnostic mode this errors will become warnings.
With strict diagnostic mode clang will also emit errors for availability
issues in code that is not used by any of the entry points:
-.. code-block: none
-
- <>2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
-
- <>:6:9: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
+.. code-block:: console
+ <>2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
+ <>:6:9: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
Note that ``myFunction`` is reachable from both pixel and compute shader entry
points is therefore scanned twice - once for each context. The diagnostic is
emitted only for the compute shader context.
>From cea5535f9d5f652f47ae52d360e1f8bf413d72ee Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Thu, 16 May 2024 22:21:19 -0700
Subject: [PATCH 7/8] Update title level and few more formatting changes
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 710fc3aa92b8d..29b638fc91b8b 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -64,9 +64,10 @@ For the example below, the ``WaveActiveCountBits`` API
function became available
The availability of ``ddx`` function depends on a shader stage. It is
available for pixel shaders in shader model 2.1 and higher, for compute, mesh
and amplification shaders in shader model 6.6 and higher. For any other shader
stages it is not available.
Compute shader example
-----------------------
+======================
.. code-block:: c++
+
float unusedFunction(float f) {
return ddx(f);
}
@@ -77,25 +78,28 @@ Compute shader example
float f2 = WaveActiveCountBits(threadId.y == 1.0);
}
-When compiled as compute shader version 5.0, clang will emit the following
error by default:
+When compiled as compute shader for shader model version 5.0, Clang will emit
the following error by default:
.. code-block:: console
+
<>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
<>:8:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
With relaxed diagnostic mode this errors will become warnings.
-With strict diagnostic mode, in addition to the 2 errors above clang will also
emit error for the ``ddx`` call in ``unusedFunction``.:
+With strict diagnostic mode, in addition to the 2 errors above Clang will also
emit error for the ``ddx`` call in ``unusedFunction``.:
.. code-block:: console
+
<>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
<>:7:13: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
<>:7:13: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
Shader library example
-----------------------
+======================
.. code-block:: c++
+
float myFunction(float f) {
return ddx(f);
}
@@ -117,16 +121,18 @@ Shader library example
float e = myFunction(f);
}
-When compiled as shader library version 6.4, clang will emit the following
error by default:
+When compiled as shader library vshader model version 6.4, Clang will emit the
following error by default:
.. code-block:: console
+
<>:2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.5 or newer
With relaxed diagnostic mode this errors will become warnings.
-With strict diagnostic mode clang will also emit errors for availability
issues in code that is not used by any of the entry points:
+With strict diagnostic mode Clang will also emit errors for availability
issues in code that is not used by any of the entry points:
.. code-block:: console
+
<>2:9: error: 'ddx' is only available in compute shader environment on
Shader Model 6.6 or newer
<>:6:9: error: 'WaveActiveCountBits' is only available on Shader Model 6.5
or newer
>From c7e81b62fb29425cd1b801db5ff2ad03f3da39a1 Mon Sep 17 00:00:00 2001
From: Helena Kotas <heko...@microsoft.com>
Date: Fri, 17 May 2024 09:45:05 -0700
Subject: [PATCH 8/8] Code review feedback
---
clang/docs/HLSL/AvailabilityDiagnostics.rst | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/clang/docs/HLSL/AvailabilityDiagnostics.rst
b/clang/docs/HLSL/AvailabilityDiagnostics.rst
index 29b638fc91b8b..3f1160bd3bf25 100644
--- a/clang/docs/HLSL/AvailabilityDiagnostics.rst
+++ b/clang/docs/HLSL/AvailabilityDiagnostics.rst
@@ -16,7 +16,7 @@ There are three modes of HLSL availability diagnostic:
#. **Relaxed mode** - same as default mode except the compiler emits a
warning. This mode is enabled by ``-Wno-error=hlsl-availability``.
-#. **Strict mode** - compiler emits an error when an unavailable API is found
in parsed code regardless of whether it can be reached from the shader entry
point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-diagnostics``.
+#. **Strict mode** - compiler emits an error when an unavailable API is found
in parsed code regardless of whether it can be reached from the shader entry
point or exported functions, or not. This mode is enabled by
``-fhlsl-strict-availability``.
Implementation Details
======================
@@ -33,9 +33,7 @@ Default and Relaxed Diagnostic Modes
This mode is implemented in ``DiagnoseHLSLAvailability`` class in
``SemaHLSL.cpp`` and it is invoked after the whole translation unit is parsed
(from ``Sema::ActOnEndOfTranslationUnit``). The implementation iterates over
all shader entry points and exported library functions in the translation unit
and performs an AST traversal of each function body.
-When a reference to another function or member method is found
(``DeclRefExpr`` or ``MemberExpr``) and it has a body, the AST of the
referenced function is also scanned. This chain of AST traversals will reach
all of the code that is reachable from the initial shader entry point or
exported library function.
-
-Another approach would be to construct a call graph by traversing the AST and
recording caller and callee for each ``CallExpr``. The availability diagnostics
would then run on the call graph. Since Clang currently does not build any call
graph during compilation, this seems like an unnecessary step. Traversing all
function references (``DeclRefExpr`` or ``MemberExpr``) works just as well, and
can be easily extended to support availability diagnostic of classes and other
AST nodes.
+When a reference to another function or member method is found
(``DeclRefExpr`` or ``MemberExpr``) and it has a body, the AST of the
referenced function is also scanned. This chain of AST traversals will reach
all of the code that is reachable from the initial shader entry point or
exported library function and avoids the need to generate a call graph.
All shader APIs have an availability attribute that specifies the shader model
version (and environment, if applicable) when this API was first
introduced.When a reference to a function without a definition is found and it
has an availability attribute, the version of the attribute is checked against
the target shader model version and shader stage (if shader stage context is
known), and an appropriate diagnostic is generated as needed.
@@ -67,7 +65,7 @@ Compute shader example
======================
.. code-block:: c++
-
+
float unusedFunction(float f) {
return ddx(f);
}
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