[MIPS] Use ABI to determine stack alignment.

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

Reviewers: sdardis

Reviewed By: sdardis

Subscribers: atanasyan, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D36326

llvm-svn: 310768
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.h b/llvm/lib/Target/Mips/MipsSubtarget.h
index cce3b8c..ef04c93 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.h
+++ b/llvm/lib/Target/Mips/MipsSubtarget.h
@@ -295,7 +295,9 @@
   // 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;
diff --git a/llvm/test/CodeGen/Mips/stack-alignment.ll b/llvm/test/CodeGen/Mips/stack-alignment.ll
index b18f966..619550f 100644
--- a/llvm/test/CodeGen/Mips/stack-alignment.ll
+++ b/llvm/test/CodeGen/Mips/stack-alignment.ll
@@ -1,9 +1,11 @@
 ; 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: