llvmorg-github-actions[bot] wrote:

<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Michael Kruse (Meinersbur)

<details>
<summary>Changes</summary>

The original #<!-- -->218802 was reverted in #<!-- -->225416 because it 
introduced $O(n^2)$ behavior in the number of driver inputs.

Fix by storing the final phase in the Compilation object instead of recomputing 
it every time when needed. Also fixes a potential inconsistency in 
`BuildOffloadingActions` which does not have the full list of inputs available 
to accurately determine the final action.

The alternative to adding members to the Compilation object would have been to 
pass 2 new arguments through a lot of calls. IMHO the Compilation should also 
store the input list, as it is specific to a compilation invocation. It already 
includes two lists (raw and translated) of arguments from which the inputs are 
derived, i.e. the input lists are already specific to the Compilation object.

`getFinalPhase` has already a TODO that wants it to be folded into the more 
comprehensive clang/Driver/Types.h mechanism. This is out of scope of this PR.


---
Full diff: https://github.com/llvm/llvm-project/pull/225678.diff


7 Files Affected:

- (modified) clang/include/clang/Driver/Compilation.h (+17) 
- (modified) clang/include/clang/Driver/Driver.h (+6-1) 
- (modified) clang/include/clang/Driver/Types.h (+4-3) 
- (modified) clang/lib/Driver/Driver.cpp (+54-14) 
- (modified) clang/lib/Driver/Types.cpp (+4-2) 
- (added) clang/test/Driver/Inputs/object0.o () 
- (added) clang/test/Driver/pch-inputs.h (+46) 


``````````diff
diff --git a/clang/include/clang/Driver/Compilation.h 
b/clang/include/clang/Driver/Compilation.h
index 825806b6cfe33..f98fc66b6cb1b 100644
--- a/clang/include/clang/Driver/Compilation.h
+++ b/clang/include/clang/Driver/Compilation.h
@@ -13,6 +13,7 @@
 #include "clang/Basic/OffloadArch.h"
 #include "clang/Driver/Action.h"
 #include "clang/Driver/Job.h"
+#include "clang/Driver/Phases.h"
 #include "clang/Driver/Util.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
@@ -68,6 +69,13 @@ class Compilation {
   /// own argument translation.
   llvm::opt::DerivedArgList *TranslatedArgs;
 
+  /// Which compilation phase is supposed to be the last job.
+  phases::ID FinalPhase;
+
+  /// Which compiler argument determined what the \p FinalPhase should be (used
+  /// for diagnostics).
+  llvm::opt::Arg *FinalPhaseArg = nullptr;
+
   /// The list of actions we've created via MakeAction.  This is not accessible
   /// to consumers; it's here just to manage ownership.
   std::vector<std::unique_ptr<Action>> AllActions;
@@ -201,6 +209,15 @@ class Compilation {
 
   llvm::opt::DerivedArgList &getArgs() { return *TranslatedArgs; }
 
+  void setFinalPhase(phases::ID FinalPhase, llvm::opt::Arg *FinalPhaseArg) {
+    this->FinalPhase = FinalPhase;
+    this->FinalPhaseArg = FinalPhaseArg;
+  }
+
+  phases::ID getFinalPhase() const { return FinalPhase; }
+
+  llvm::opt::Arg *getFinalPhaseArg() const { return FinalPhaseArg; }
+
   ActionList &getActions() { return Actions; }
   const ActionList &getActions() const { return Actions; }
 
diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 15b6fdcb8a574..fa4eef66e3dea 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -332,15 +332,20 @@ class Driver {
   LLVM_PREFERRED_TYPE(bool)
   unsigned ProbePrecompiled : 1;
 
-public:
   // getFinalPhase - Determine which compilation mode we are in and record
   // which option we used to determine the final phase.
   // TODO: Much of what getFinalPhase returns are not actually true compiler
   //       modes. Fold this functionality into Types::getCompilationPhases and
   //       handleArguments.
   phases::ID getFinalPhase(const llvm::opt::DerivedArgList &DAL,
+                           llvm::ArrayRef<InputTy>,
                            llvm::opt::Arg **FinalPhaseArg = nullptr) const;
 
+  /// Set the final phase in \p C based on compiler arguments, driver state, 
and
+  /// the \p Inputs to be processed.
+  void updateFinalPhase(Compilation &C, llvm::ArrayRef<InputTy> Inputs) const;
+
+public:
   llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
   executeProgram(llvm::ArrayRef<llvm::StringRef> Args) const;
 
diff --git a/clang/include/clang/Driver/Types.h 
b/clang/include/clang/Driver/Types.h
index 9dd89e1904a4f..e4f3536ed1c6e 100644
--- a/clang/include/clang/Driver/Types.h
+++ b/clang/include/clang/Driver/Types.h
@@ -115,9 +115,10 @@ namespace types {
   /// done for type 'Id' up until including LastPhase.
   llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases>
   getCompilationPhases(ID Id, phases::ID LastPhase = phases::IfsMerge);
-  llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases>
-  getCompilationPhases(const clang::driver::Driver &Driver,
-                       llvm::opt::DerivedArgList &DAL, ID Id);
+  llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> 
getCompilationPhases(
+      const clang::driver::Driver &Driver, llvm::opt::DerivedArgList &DAL,
+      llvm::ArrayRef<std::pair<ID, const llvm::opt::Arg *>> Inputs, ID Id,
+      phases::ID FinalPhase);
 
   /// lookupCXXTypeForCType - Lookup CXX input type that corresponds to given
   /// C type (used for clang++ emulation of g++ behaviour)
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 7649941a68b1c..cba622553a3f3 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -352,8 +352,10 @@ InputArgList Driver::ParseArgStrings(ArrayRef<const char 
*> ArgStrings,
 
 // Determine which compilation mode we are in. We look for options which
 // affect the phase, starting with the earliest phases, and record which
-// option we used to determine the final phase.
+// option we used to determine the final phase. In absence of any explicit
+// action command line option, derive the compilation mode from the inputs.
 phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
+                                 llvm::ArrayRef<InputTy> Inputs,
                                  Arg **FinalPhaseArg) const {
   Arg *PhaseArg = nullptr;
   phases::ID FinalPhase;
@@ -401,9 +403,33 @@ phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
   } else if ((PhaseArg = DAL.getLastArg(options::OPT_emit_interface_stubs))) {
     FinalPhase = phases::IfsMerge;
 
-    // Otherwise do everything.
-  } else
-    FinalPhase = phases::Link;
+    // Otherwise autodetect from last phase triggered by input file.
+  } else {
+    FinalPhase = phases::Preprocess;
+    bool AnyPhase = false;
+    for (auto &I : Inputs) {
+      types::ID InputType = I.first;
+      const Arg *InputArg = I.second;
+
+      // Linker options should not trigger more phases.
+      if (InputArg->getOption().hasFlag(options::LinkerInput))
+        continue;
+
+      // Relies on the compilation phases being ordered.
+      auto PL = types::getCompilationPhases(InputType);
+      if (PL.empty())
+        continue;
+
+      phases::ID LastPL = PL.back();
+      if (LastPL > FinalPhase)
+        FinalPhase = LastPL;
+      AnyPhase = true;
+    }
+
+    // Fall back to "do everything" when consistency check fails.
+    if (!AnyPhase || FinalPhase > phases::Link)
+      FinalPhase = phases::Link;
+  }
 
   if (FinalPhaseArg)
     *FinalPhaseArg = PhaseArg;
@@ -411,6 +437,13 @@ phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
   return FinalPhase;
 }
 
+void Driver::updateFinalPhase(Compilation &C,
+                              llvm::ArrayRef<InputTy> Inputs) const {
+  Arg *FinalPhaseArg = nullptr;
+  phases::ID FinalPhase = getFinalPhase(C.getArgs(), Inputs, &FinalPhaseArg);
+  C.setFinalPhase(FinalPhase, FinalPhaseArg);
+}
+
 llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
 Driver::executeProgram(llvm::ArrayRef<llvm::StringRef> Args) const {
   llvm::SmallString<64> OutputFile;
@@ -1847,13 +1880,17 @@ Compilation *Driver::BuildCompilation(ArrayRef<const 
char *> ArgList) {
   // Construct the list of inputs.
   InputList Inputs;
   BuildInputs(C->getDefaultToolChain(), *TranslatedArgs, Inputs);
+  updateFinalPhase(*C, Inputs);
+  phases::ID FinalPhase = C->getFinalPhase();
+
   if (HasConfigFileTail && Inputs.size()) {
-    Arg *FinalPhaseArg;
-    if (getFinalPhase(*TranslatedArgs, &FinalPhaseArg) == phases::Link) {
+    if (FinalPhase == phases::Link) {
       DerivedArgList TranslatedLinkerIns(*CfgOptionsTail);
       for (Arg *A : *CfgOptionsTail)
         TranslatedLinkerIns.append(A);
       BuildInputs(C->getDefaultToolChain(), TranslatedLinkerIns, Inputs);
+      updateFinalPhase(*C, Inputs);
+      FinalPhase = C->getFinalPhase();
     }
   }
 
@@ -2121,6 +2158,7 @@ void Driver::generateCompilationDiagnostics(
   // Construct the list of inputs.
   InputList Inputs;
   BuildInputs(C.getDefaultToolChain(), C.getArgs(), Inputs);
+  updateFinalPhase(C, Inputs);
 
   ArgStringList IRInputs;
   for (InputList::iterator it = Inputs.begin(), ie = Inputs.end(); it != ie;) {
@@ -3433,8 +3471,8 @@ void Driver::handleArguments(Compilation &C, 
DerivedArgList &Args,
     YcArg = nullptr;
   }
 
-  Arg *FinalPhaseArg;
-  phases::ID FinalPhase = getFinalPhase(Args, &FinalPhaseArg);
+  phases::ID FinalPhase = C.getFinalPhase();
+  llvm::opt::Arg *FinalPhaseArg = C.getFinalPhaseArg();
 
   if (FinalPhase == phases::Link) {
     if (Args.hasArgNoClaim(options::OPT_hipstdpar)) {
@@ -3532,7 +3570,7 @@ void Driver::handleArguments(Compilation &C, 
DerivedArgList &Args,
         Diag(clang::diag::warn_drv_input_file_unused)
             << InputArg->getAsString(Args) << getPhaseName(InitialPhase)
             << !!FinalPhaseArg
-            << (FinalPhaseArg ? FinalPhaseArg->getOption().getName() : "");
+            << (FinalPhaseArg ? FinalPhaseArg->getSpelling() : "");
       continue;
     }
 
@@ -3609,12 +3647,12 @@ void Driver::BuildActions(Compilation &C, 
DerivedArgList &Args,
   Args.ClaimAllArgs(options::OPT_no_offload_new_driver);
   Args.ClaimAllArgs(options::OPT_offload_new_driver);
 
+  phases::ID FinalPhase = C.getFinalPhase();
   bool HIPRDCDeviceOnlyFatBin =
       C.isOffloadingHostKind(Action::OFK_HIP) && offloadDeviceOnly() &&
       Args.hasArg(options::OPT_hip_link) &&
       Args.hasFlag(options::OPT_fgpu_rdc, options::OPT_fno_gpu_rdc, false) &&
-      getFinalPhase(Args) == phases::Link &&
-      !Args.hasArg(options::OPT_emit_llvm) &&
+      FinalPhase == phases::Link && !Args.hasArg(options::OPT_emit_llvm) &&
       Args.hasFlag(options::OPT_gpu_bundle_output,
                    options::OPT_no_gpu_bundle_output, true);
 
@@ -3627,7 +3665,8 @@ void Driver::BuildActions(Compilation &C, DerivedArgList 
&Args,
     types::ID InputType = I.first;
     const Arg *InputArg = I.second;
 
-    auto PL = types::getCompilationPhases(*this, Args, InputType);
+    auto PL =
+        types::getCompilationPhases(*this, Args, Inputs, InputType, 
FinalPhase);
     if (PL.empty())
       continue;
 
@@ -4125,7 +4164,7 @@ Driver::BuildOffloadingActions(Compilation &C, 
llvm::opt::DerivedArgList &Args,
   // Don't build offloading actions if we do not have a compile action. If
   // preprocessing only ignore embedding.
   if (!(isa<CompileJobAction>(HostAction) ||
-        getFinalPhase(Args) == phases::Preprocess))
+        C.getFinalPhase() == phases::Preprocess))
     return HostAction;
 
   bool UsesLLVMOffloading = Args.hasArg(
@@ -4178,7 +4217,8 @@ Driver::BuildOffloadingActions(Compilation &C, 
llvm::opt::DerivedArgList &Args,
             .isOSDarwin())
       HostAction->setCannotBeCollapsedWithNextDependentAction();
 
-    auto PL = types::getCompilationPhases(*this, Args, InputType);
+    auto PL = types::getCompilationPhases(*this, Args, {Input}, InputType,
+                                          C.getFinalPhase());
 
     for (phases::ID Phase : PL) {
       if (Phase == phases::Link) {
diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
index 4cca8acd515d7..e04d3c9a05ace 100644
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -429,8 +429,10 @@ types::getCompilationPhases(ID Id, phases::ID LastPhase) {
 
 llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases>
 types::getCompilationPhases(const clang::driver::Driver &Driver,
-                            llvm::opt::DerivedArgList &DAL, ID Id) {
-  return types::getCompilationPhases(Id, Driver.getFinalPhase(DAL));
+                            llvm::opt::DerivedArgList &DAL,
+                            llvm::ArrayRef<InputTy> Inputs, ID Id,
+                            phases::ID FinalPhase) {
+  return types::getCompilationPhases(Id, FinalPhase);
 }
 
 ID types::lookupCXXTypeForCType(ID Id) {
diff --git a/clang/test/Driver/Inputs/object0.o 
b/clang/test/Driver/Inputs/object0.o
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/clang/test/Driver/pch-inputs.h b/clang/test/Driver/pch-inputs.h
new file mode 100644
index 0000000000000..a1108e7bba40d
--- /dev/null
+++ b/clang/test/Driver/pch-inputs.h
@@ -0,0 +1,46 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+
+// Warn about linker options being ignored when not linking
+// RUN: %clang %s -lfoo -o %t/tmp1.pch -### 2>&1 | FileCheck %s 
--check-prefix=UNUSED-L,SINGLEHEADER
+// RUN: %clang %s -x c++-header -lfoo -o %t/tmp1.pch -### 2>&1 | FileCheck %s 
--check-prefix=UNUSED-L,SINGLEHEADER
+// UNUSED-L: clang: warning: -lfoo: 'linker' input unused when '' is present 
[-Wunused-command-line-argument]
+
+// RUN: %clang %s -Wl,--whole-archive -o %t/tmp1.pch -### 2>&1 | FileCheck %s 
--check-prefix=UNUSED-WL,SINGLEHEADER
+// UNUSED-WL: clang: warning: -Wl,--whole-archive: 'linker' input unused when 
'' is present [-Wunused-command-line-argument]
+
+// RUN: %clang %S/Inputs/header1.h %S/Inputs/header2.h -lfoo -### 2>&1 | 
FileCheck %s --check-prefix=UNUSED-L,MULTIHEADER
+
+
+// Error with single -o when there are multiple output files
+// RUN: not %clang %S/Inputs/header1.h %S/Inputs/header2.h -lfoo -o 
%t/tmp2.pch -### 2>&1 | FileCheck %s --check-prefix=UNUSED-L,MULTIOUTPUT
+// MULTIOUTPUT: clang: error: cannot specify -o when generating multiple 
output files
+
+// An actual linker input file (object0.o) triggers an error, not a warning
+// RUN: not %clang %s %S/Inputs/object0.o -o %t/tmp3.pch -### 2>&1 | FileCheck 
%s --check-prefix=MULTIOUTPUT
+
+// Other input types that do not link
+// RUN: %clang -x cl-header %s -Xlinker -somelinkerflag -### 2>&1 | FileCheck 
%s --check-prefix=UNUSED-XLINKER
+// RUN: %clang -x objective-c++-header %s -Xlinker -somelinkerflag -### 2>&1 | 
FileCheck %s --check-prefix=UNUSED-XLINKER
+// RUN: %clang -x hlsl %s -Xlinker -somelinkerflag -### 2>&1 | FileCheck %s 
--check-prefix=UNUSED-XLINKER
+// UNUSED-XLINKER: clang: warning: -Xlinker -somelinkerflag: 'linker' input 
unused when '' is present [-Wunused-command-line-argument]
+
+
+// Normal case: Single header file input compiles to .pch even without 
--precompile
+// RUN: %clang %s -o %t/tmp1.pch -### 2>&1 | FileCheck %s 
--check-prefix=SINGLEHEADER
+// SINGLEHEADER: "-cc1"
+// SINGLEHEADER: "-emit-pch"
+// SINGLEHEADER: "-o"
+// SINGLEHEADER: tmp1.pch"
+
+
+// Multiple header files input compiles to one .pch each even without 
--precompile
+// RUN: %clang %S/Inputs/header1.h %S/Inputs/header2.h -### 2>&1 | FileCheck 
%s --check-prefix=MULTIHEADER
+// MULTIHEADER: "-cc1"
+// MULTIHEADER: "-emit-pch"
+// MULTIHEADER: "-o"
+// MULTIHEADER: header1.h.pch"
+// MULTIHEADER: "-cc1"
+// MULTIHEADER: "-emit-pch"
+// MULTIHEADER: "-o"
+// MULTIHEADER: header2.h.pch"

``````````

</details>


https://github.com/llvm/llvm-project/pull/225678
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