[PATCH] D51026: [CodeGen] Implicitly set stackrealign on the main function, if custom stack alignment is used

[Martin Storsjö via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL340334: [CodeGen] Implicitly set stackrealign on the main function, if custom stack… (authored by mstorsjo, committed by ).
Herald added a subscriber: llvm-commits.

Changed prior to commit:
  https://reviews.llvm.org/D51026?vs=161653&id=161809#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D51026

Files:
  cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
  cfe/trunk/test/CodeGen/stackrealign-main.c


Index: cfe/trunk/test/CodeGen/stackrealign-main.c
===================================================================
--- cfe/trunk/test/CodeGen/stackrealign-main.c
+++ cfe/trunk/test/CodeGen/stackrealign-main.c
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm -o - -mstack-alignment=64 %s | FileCheck %s
+
+// CHECK-LABEL: define void @other()
+// CHECK: [[OTHER:#[0-9]+]]
+// CHECK: {
+void other(void) {}
+
+// CHECK-LABEL: define i32 @main(
+// CHECK: [[MAIN:#[0-9]+]]
+// CHECK: {
+int main(int argc, char **argv) {
+  other();
+  return 0;
+}
+
+// CHECK: attributes [[OTHER]] = { noinline nounwind optnone
+// CHECK-NOT: "stackrealign"
+// CHECK: }
+// CHECK: attributes [[MAIN]] = { noinline nounwind optnone {{.*}}"stackrealign"{{.*}} }
Index: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp
@@ -979,6 +979,13 @@
       if (FD->isMain())
         Fn->addFnAttr(llvm::Attribute::NoRecurse);
 
+  // If a custom alignment is used, force realigning to this alignment on
+  // any main function which certainly will need it.
+  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
+    if ((FD->isMain() || FD->isMSVCRTEntryPoint()) &&
+        CGM.getCodeGenOpts().StackAlignment)
+      Fn->addFnAttr("stackrealign");
+
   llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
 
   // Create a marker to make it easy to insert allocas into the entryblock


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