[CodeGen][x86_64] Enable 'force_align_arg_pointer' attribute at x86_64
This attribute is useful in OS development when we jump from 32 to 64 bit
code and expect that 64bit function forces correct stack alignment.
Related discussion: http://lists.llvm.org/pipermail/cfe-dev/2017-June/054358.html
Patch By: anatol.pomozov (anatol.pomozov@gmail.com)
Differential Revision:https://reviews.llvm.org/D36272
llvm-svn: 312173
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 77b9b4c..10fa2ea 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -2297,6 +2297,15 @@
if (!IsForDefinition)
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);
+ }
if (FD->hasAttr<AnyX86InterruptAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
Fn->setCallingConv(llvm::CallingConv::X86_INTR);
@@ -2425,6 +2434,15 @@
if (!IsForDefinition)
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);
+ }
if (FD->hasAttr<AnyX86InterruptAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
Fn->setCallingConv(llvm::CallingConv::X86_INTR);