Commit 64dcc854 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r330331: 

------------------------------------------------------------------------
r330331 | erichkeane | 2018-04-19 07:27:05 -0700 (Thu, 19 Apr 2018) | 14 lines

Fix __attribute__((force_align_arg_pointer)) misalignment bug

The force_align_arg_pointer attribute was using a hardcoded 16-byte
alignment value which in combination with -mstack-alignment=32 (or
larger) would produce a misaligned stack which could result in crashes
when accessing stack buffers using aligned AVX load/store instructions.

Fix the issue by using the "stackrealign" function attribute instead
of using a hardcoded 16-byte alignment.

Patch By: Gramner

Differential Revision: https://reviews.llvm.org/D45812

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llvm-svn: 333511
parent aaa7a7a2

clang/lib/CodeGen/TargetInfo.cpp

+5 −20
Original line number Diff line number Diff line
@@ -1931,13 +1931,8 @@ void X86_32TargetCodeGenInfo::setTargetAttributes( 
    return;

  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {

    if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {

      // Get the LLVM function.

      llvm::Function *Fn = cast<llvm::Function>(GV);



      // Now add the 'alignstack' attribute with a value of 16.

      llvm::AttrBuilder B;

      B.addStackAlignmentAttr(16);

      Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);

      Fn->addFnAttr("stackrealign");

    }

    if (FD->hasAttr<AnyX86InterruptAttr>()) {

      llvm::Function *Fn = cast<llvm::Function>(GV);
@@ -2292,13 +2287,8 @@ public: 
      return;

    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {

      if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {

        // Get the LLVM function.

        auto *Fn = cast<llvm::Function>(GV);



        // Now add the 'alignstack' attribute with a value of 16.

        llvm::AttrBuilder B;

        B.addStackAlignmentAttr(16);

        Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);

        llvm::Function *Fn = cast<llvm::Function>(GV);

        Fn->addFnAttr("stackrealign");

      }

      if (FD->hasAttr<AnyX86InterruptAttr>()) {

        llvm::Function *Fn = cast<llvm::Function>(GV);
@@ -2429,13 +2419,8 @@ void WinX86_64TargetCodeGenInfo::setTargetAttributes( 
    return;

  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {

    if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {

      // Get the LLVM function.

      auto *Fn = cast<llvm::Function>(GV);



      // Now add the 'alignstack' attribute with a value of 16.

      llvm::AttrBuilder B;

      B.addStackAlignmentAttr(16);

      Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);

      llvm::Function *Fn = cast<llvm::Function>(GV);

      Fn->addFnAttr("stackrealign");

    }

    if (FD->hasAttr<AnyX86InterruptAttr>()) {

      llvm::Function *Fn = cast<llvm::Function>(GV);

clang/test/CodeGen/function-attributes.c

+2 −2
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ void f15(void) { 


// PR5254

// CHECK-LABEL: define void @f16

// CHECK: [[ALIGN:#[0-9]+]]

// CHECK: [[SR:#[0-9]+]]

// CHECK: {

void __attribute__((force_align_arg_pointer)) f16(void) {

}
@@ -112,7 +112,7 @@ void f20(void) { 
// CHECK: attributes [[NUW]] = { nounwind optsize{{.*}} }

// CHECK: attributes [[AI]] = { alwaysinline nounwind optsize{{.*}} }

// CHECK: attributes [[NUW_OS_RN]] = { nounwind optsize readnone{{.*}} }

// CHECK: attributes [[ALIGN]] = { nounwind optsize alignstack=16{{.*}} }

// CHECK: attributes [[SR]] = { nounwind optsize{{.*}} "stackrealign"{{.*}} }

// CHECK: attributes [[RT]] = { nounwind optsize returns_twice{{.*}} }

// CHECK: attributes [[NR]] = { noreturn optsize }

// CHECK: attributes [[NUW_RN]] = { nounwind optsize readnone }