[MIPS] Use ABI to determine stack alignment.

[bsdjhb]

Summary

The stack alignment depends on the ABI (16 bytes for N32 and N64 and 8
bytes for O32), not the CPU type.

[atanasyan]

Could you add test cases?

[sdardis]

Specifically, can you extend test/CodeGen/Mips/stack-alignment.ll to cover mips3 and mips4 with the n64 abi?

[bsdjhb]

Add tests for older -mcpu arguments with N64 ABI.

[sdardis]

LGTM.

[sdardis]

test/CodeGen/Mips/stack-alignment.ll

8

That needs to be daddiu.

[bsdjhb]

• Use daddiu for 64-bit.

[sdardis]

You need me to commit this for you?

lib/Target/Mips/MipsSubtarget.h

public:
   bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
 
   bool isXRaySupported() const override { return true; }
 
   // for now constant islands are on for the whole compilation unit but we only
   // really use them if in addition we are in mips16 mode
   static bool useConstantIslands();
 
-  unsigned stackAlignment() const { return hasMips64() ? 16 : 8; }
+  unsigned stackAlignment() const {
+    return isABI_N32() || isABI_N64() ? 16 : 8;
+  }
 
   // Grab relocation model
   Reloc::Model getRelocationModel() const;
 
   MipsSubtarget &initializeSubtargetDependencies(StringRef CPU, StringRef FS,
                                                  const TargetMachine &TM);
 
   /// Does the system support unaligned memory access.

test/CodeGen/Mips/stack-alignment.ll

 ; RUN: llc -march=mipsel < %s | FileCheck %s -check-prefix=32
 ; RUN: llc -march=mipsel -mattr=+fp64 < %s | FileCheck %s -check-prefix=32
+; RUN: llc -march=mips64el -mcpu=mips3 < %s | FileCheck %s -check-prefix=64
+; RUN: llc -march=mips64el -mcpu=mips4 < %s | FileCheck %s -check-prefix=64
 ; RUN: llc -march=mips64el -mcpu=mips64 < %s | FileCheck %s -check-prefix=64
 
 ; 32:      addiu  $sp, $sp, -8
-; 64:      addiu  $sp, $sp, -16
+; 64:      daddiu  $sp, $sp, -16
 
 define i32 @foo1() #0 {
 entry:
   ret i32 14
 }
 
 attributes #0 = { "no-frame-pointer-elim"="true" }