[AArch64][GlobalISel] Any-extend vararg parameters to stack slot size on Darwin.

We currently don't any-extend vararg parameters before storing them to the stack
locations on Darwin. However, SelectionDAG however does this, and so user code
is in the wild which inadvertently relies on this extension. This can manifest
in cases where the value stored is (int)0, but the actual parameter is interpreted
by va_arg as a pointer, and so not extending to 64 bits causes the callee to
load additional undefined bits.

llvm-svn: 336120

diff --git a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
index e4dc10c..b8644ba 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64CallLowering.cpp
@@ -155,6 +155,9 @@ struct OutgoingArgHandler : public CallLowering::ValueHandler {
 
   void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
                             MachinePointerInfo &MPO, CCValAssign &VA) override {
+    if (VA.getLocInfo() == CCValAssign::LocInfo::AExt)
+      Size = VA.getLocVT().getSizeInBits() / 8;
+
     auto MMO = MIRBuilder.getMF().getMachineMemOperand(
         MPO, MachineMemOperand::MOStore, Size, 0);
     MIRBuilder.buildStore(ValVReg, Addr, *MMO);

diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/arm64-callingconv-ios.ll b/llvm/test/CodeGen/AArch64/GlobalISel/arm64-callingconv-ios.ll
index b74b632..9e4015a 100644 (file)
--- a/llvm/test/CodeGen/AArch64/GlobalISel/arm64-callingconv-ios.ll
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/arm64-callingconv-ios.ll
@@ -16,9 +16,9 @@ target triple = "aarch64-apple-ios9.0"
 ; CHECK: $w0 = COPY [[ANSWER]]
 ; CHECK: $d0 = COPY [[D_ONE]]
 ; CHECK: $x1 = COPY [[TWELVE]]
-; CHECK: G_STORE [[THREE]](s8), {{%[0-9]+}}(p0) :: (store 1 into stack, align 0)
-; CHECK: G_STORE [[ONE]](s16), {{%[0-9]+}}(p0) :: (store 2 into stack + 8, align 0)
-; CHECK: G_STORE [[FOUR]](s32), {{%[0-9]+}}(p0) :: (store 4 into stack + 16, align 0)
+; CHECK: G_STORE [[THREE]](s8), {{%[0-9]+}}(p0) :: (store 8 into stack, align 0)
+; CHECK: G_STORE [[ONE]](s16), {{%[0-9]+}}(p0) :: (store 8 into stack + 8, align 0)
+; CHECK: G_STORE [[FOUR]](s32), {{%[0-9]+}}(p0) :: (store 8 into stack + 16, align 0)
 ; CHECK: G_STORE [[F_ONE]](s32), {{%[0-9]+}}(p0) :: (store 4 into stack + 24, align 0)
 ; CHECK: G_STORE [[TWO]](s64), {{%[0-9]+}}(p0) :: (store 8 into stack + 32, align 0)
 declare void @varargs(i32, double, i64, ...)