https://github.com/antangelo created
https://github.com/llvm/llvm-project/pull/65662:
Adds documentation for the X86 `__attribute__((interrupt))` attribute, in a
similar format to interrupt attributes of
other platforms.
>From 96db4e211cabae972fd3dfe476c23c6377b9f5df Mon Sep 17 00:00:00 2001
From: Antonio Abbatangelo <cont...@antangelo.com>
Date: Thu, 31 Aug 2023 16:40:06 -0400
Subject: [PATCH] [clang][Docs] Document X86 interrupt attribute
---
clang/include/clang/Basic/Attr.td | 2 +-
clang/include/clang/Basic/AttrDocs.td | 48 +++++++++++++++++++++++++++
2 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/clang/include/clang/Basic/Attr.td
b/clang/include/clang/Basic/Attr.td
index 4f281c5c8bdec3b..c09d0ca5c6d3a6a 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -3113,7 +3113,7 @@ def AnyX86Interrupt : InheritableAttr,
TargetSpecificAttr<TargetAnyX86> {
let Subjects = SubjectList<[HasFunctionProto]>;
let ParseKind = "Interrupt";
let HasCustomParsing = 1;
- let Documentation = [Undocumented];
+ let Documentation = [AnyX86InterruptDocs];
}
def AnyX86NoCallerSavedRegisters : InheritableAttr,
diff --git a/clang/include/clang/Basic/AttrDocs.td
b/clang/include/clang/Basic/AttrDocs.td
index f11ea89d14bad0d..c3fe7cea29afbf1 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -4801,6 +4801,54 @@ Marking virtual functions as ``disable_tail_calls`` is
legal.
}];
}
+def AnyX86InterruptDocs : Documentation {
+ let Category = DocCatFunction;
+ let Heading = "interrupt (X86)";
+ let Content = [{
+Clang supports the GNU style ``__attribute__((interrupt))`` attribute on X86
+targets. This attribute may be attached to a function definition and instructs
+the backend to generate appropriate function entry/exit code so that it can be
+used directly as an interrupt service routine.
+
+Interrupt handlers have access to the stack frame pushed onto the stack by the
processor,
+and return using the ``IRET`` instruction. All registers in an interrupt
handler are callee-saved.
+Exception handlers also have access to the error code pushed onto the stack by
the processor,
+when applicable.
+
+An interrupt handler must take the following arguments:
+
+ .. code-block:: c
+
+ __attribute__ ((interrupt))
+ void f (struct stack_frame *frame) {
+ ...
+ }
+
+ Where ``struct stack_frame`` is a suitable struct matching the stack frame
pushed by the
+ processor.
+
+An exception handler must take the following arguments:
+
+ .. code-block:: c
+
+ __attribute__ ((interrupt))
+ void g (struct stack_frame *frame, unsigned long code) {
+ ...
+ }
+
+ On 32-bit targets, the ``code`` argument should be of type ``unsigned int``.
+
+Exception handlers should only be used when an error code is pushed by the
processor.
+Using the incorrect handler type will crash the system.
+
+Interrupt and exception handlers cannot be called by other functions and must
have return type ``void``.
+
+Interrupt and exception handlers should only call functions with the
'no_caller_saved_registers'
+attribute, or should be compiled with the '-mgeneral-regs-only' flag to avoid
saving unused
+non-GPR registers.
+ }];
+}
+
def AnyX86NoCallerSavedRegistersDocs : Documentation {
let Category = DocCatFunction;
let Content = [{
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