[NVPTXAsmPrinter] do not print .align on function headers

Summary:
PTX does not allow .align directives on function headers.

Fixes PR21551.

Test Plan: test/Codegen/NVPTX/function-align.ll

Reviewers: eliben, jholewinski

Reviewed By: eliben, jholewinski

Subscribers: llvm-commits, eliben, jpienaar, jholewinski

Differential Revision: http://reviews.llvm.org/D8274

llvm-svn: 232004

5 files changed, 17 insertions, 1 deletions

diff --git a/llvm/include/llvm/MC/MCAsmInfo.h b/llvm/include/llvm/MC/MCAsmInfo.h
index 1e9817ea48d..658d77cbddf 100644
--- a/llvm/include/llvm/MC/MCAsmInfo.h
+++ b/llvm/include/llvm/MC/MCAsmInfo.h
@@ -256,6 +256,10 @@ protected:
   /// argument and how it is interpreted.  Defaults to NoAlignment.
   LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
 
+  // True if the target allows .align directives on funtions. This is true for
+  // most targets, so defaults to true.
+  bool HasFunctionAlignment;
+
   /// True if the target has .type and .size directives, this is true for most
   /// ELF targets.  Defaults to true.
   bool HasDotTypeDotSizeDirective;
@@ -467,6 +471,7 @@ public:
   LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
     return LCOMMDirectiveAlignmentType;
   }
+  bool hasFunctionAlignment() const { return HasFunctionAlignment; }
   bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
   bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
   bool hasIdentDirective() const { return HasIdentDirective; }
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 3295d59cb55..4a03e5ef045 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -527,7 +527,8 @@ void AsmPrinter::EmitFunctionHeader() {
   EmitVisibility(CurrentFnSym, F->getVisibility());
 
   EmitLinkage(F, CurrentFnSym);
-  EmitAlignment(MF->getAlignment(), F);
+  if (MAI->hasFunctionAlignment())
+    EmitAlignment(MF->getAlignment(), F);
 
   if (MAI->hasDotTypeDotSizeDirective())
     OutStreamer.EmitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index 8a7ee94a593..bad257a961b 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -69,6 +69,7 @@ MCAsmInfo::MCAsmInfo() {
   HasAggressiveSymbolFolding = true;
   COMMDirectiveAlignmentIsInBytes = true;
   LCOMMDirectiveAlignmentType = LCOMM::NoAlignment;
+  HasFunctionAlignment = true;
   HasDotTypeDotSizeDirective = true;
   HasSingleParameterDotFile = true;
   HasIdentDirective = false;
diff --git a/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp b/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
index 11d737ec187..b9df3d18f94 100644
--- a/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
+++ b/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
@@ -39,6 +39,8 @@ NVPTXMCAsmInfo::NVPTXMCAsmInfo(StringRef TT) {
   InlineAsmEnd = " inline asm";
 
   SupportsDebugInformation = CompileForDebugging;
+  // PTX does not allow .align on functions.
+  HasFunctionAlignment = false;
   HasDotTypeDotSizeDirective = false;
 
   Data8bitsDirective = " .b8 ";
diff --git a/llvm/test/CodeGen/NVPTX/function-align.ll b/llvm/test/CodeGen/NVPTX/function-align.ll
new file mode 100644
index 00000000000..e7abfb128f5
--- /dev/null
+++ b/llvm/test/CodeGen/NVPTX/function-align.ll
@@ -0,0 +1,7 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s
+
+; CHECK-NOT: .align 2
+define ptx_device void @foo() align 2 {
+; CHECK-LABEL: .func foo
+  ret void
+}