[PowerPC] Mark fixed-offset byvals as pointed-to by IR values

A byval object, even if allocated at a fixed offset (prescribed by the ABI) is
pointed to by IR values. Most fixed-offset stack objects are not pointed-to by
IR values, so the default is to assume this is not possible. However, we need
to override the default in this case (instruction scheduling can cause
miscompiles otherwise).

Fixes PR20280.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215795 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 42e724d3f1e8f1d5ef84922da22d780491b0e419..3badab60aa182ad19384c4d5de6ef2e5165a27cf 100644 (file)
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -2700,7 +2700,7 @@ PPCTargetLowering::LowerFormalArguments_64SVR4(
       int FI;
       if (HasParameterArea ||
           ArgSize + ArgOffset > LinkageSize + Num_GPR_Regs * PtrByteSize)
-        FI = MFI->CreateFixedObject(ArgSize, ArgOffset, false);
+        FI = MFI->CreateFixedObject(ArgSize, ArgOffset, false, true);
       else
         FI = MFI->CreateStackObject(ArgSize, Align, false);
       SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
@@ -3066,7 +3066,7 @@ PPCTargetLowering::LowerFormalArguments_Darwin(
         CurArgOffset = CurArgOffset + (4 - ObjSize);
       }
       // The value of the object is its address.
-      int FI = MFI->CreateFixedObject(ObjSize, CurArgOffset, false);
+      int FI = MFI->CreateFixedObject(ObjSize, CurArgOffset, false, true);
       SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
       InVals.push_back(FIN);
       if (ObjSize==1 || ObjSize==2) {

diff --git a/test/CodeGen/PowerPC/byval-aliased.ll b/test/CodeGen/PowerPC/byval-aliased.ll
new file mode 100644 (file)
index 0000000..9ef2f02
--- /dev/null
+++ b/test/CodeGen/PowerPC/byval-aliased.ll
@@ -0,0 +1,30 @@
+; RUN: llc -mcpu=ppc64 < %s | FileCheck %s
+target datalayout = "E-m:o-p:32:32-f64:32:64-n32"
+target triple = "powerpc-apple-macosx10.5.0"
+ 
+%struct.sm = type { i8, i8 }
+ 
+; Function Attrs: nounwind ssp
+define void @foo(%struct.sm* byval %s) #0 {
+entry:
+  %a = getelementptr inbounds %struct.sm* %s, i32 0, i32 0
+  %0 = load i8* %a, align 1
+  %conv2 = zext i8 %0 to i32
+  %add = add nuw nsw i32 %conv2, 3
+  %conv1 = trunc i32 %add to i8
+  store i8 %conv1, i8* %a, align 1
+  call void @bar(%struct.sm* byval %s, %struct.sm* byval %s) #1
+  ret void
+}
+
+; CHECK-LABEL: @foo
+; CHECK: stb {{r[0-9]+}}, [[OFF:[0-9]+]]({{r[3]?1}})
+; CHECK: lhz r3, [[OFF]]({{r[3]?1}})
+; CHECK: bl _bar
+; CHECK: blr
+ 
+declare void @bar(%struct.sm* byval, %struct.sm* byval)
+ 
+attributes #0 = { nounwind ssp }
+attributes #1 = { nounwind }
+