R600: Fix calculation of stack offset in AMDGPUFrameLowering

We weren't computing structure size correctly and we were relying on
the original alloca instruction to compute the offset, which isn't
always reliable.

Reviewed-by: Vincent Lejeune <vljn@ovi.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183568 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 21 deletions

diff --git a/lib/Target/R600/AMDGPUFrameLowering.cpp b/lib/Target/R600/AMDGPUFrameLowering.cpp
index 815d6f71c3..40f14d2f67 100644
--- a/lib/Target/R600/AMDGPUFrameLowering.cpp
+++ b/lib/Target/R600/AMDGPUFrameLowering.cpp
@@ -78,27 +78,8 @@ int AMDGPUFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
   int UpperBound = FI == -1 ? MFI->getNumObjects() : FI;
 
   for (int i = MFI->getObjectIndexBegin(); i < UpperBound; ++i) {
-    const AllocaInst *Alloca = MFI->getObjectAllocation(i);
-    unsigned ArrayElements;
-    const Type *AllocaType = Alloca->getAllocatedType();
-    const Type *ElementType;
-
-    if (AllocaType->isArrayTy()) {
-      ArrayElements = AllocaType->getArrayNumElements();
-      ElementType = AllocaType->getArrayElementType();
-    } else {
-      ArrayElements = 1;
-      ElementType = AllocaType;
-    }
-
-    unsigned VectorElements;
-    if (ElementType->isVectorTy()) {
-      VectorElements = ElementType->getVectorNumElements();
-    } else {
-      VectorElements = 1;
-    }
-
-    Offset += (VectorElements / getStackWidth(MF)) * ArrayElements;
+    unsigned Size = MFI->getObjectSize(i);
+    Offset += (Size / (getStackWidth(MF) * 4));
   }
   return Offset;
 }