[SystemZ] Fix handling of pass-by-pointer arguments
I'd misunderstood getIndirect() to mean that the argument should be passed
as a pointer at the ABI level, with the ByVal argument choosing caller-copy
semantics over no-caller-copy (callee-copy-on-write) semantics. But
getIndirect(x) actually means that x is passed by pointer at the IR
level but (at least on all other targets I looked at) directly at the
ABI level. getIndirect(x, false) selects a pointer to a caller-made
copy, which is what SystemZ was aiming for.
This fixes a miscompilation of c-index-test. Structure arguments were being
passed by pointer, but no copy was being made, so a write in the callee
stomped over a caller's local variable.
llvm-svn: 196370
diff --git a/clang/test/CodeGen/systemz-inline-asm.c b/clang/test/CodeGen/systemz-inline-asm.c
index eb0f912..c937233 100644
--- a/clang/test/CodeGen/systemz-inline-asm.c
+++ b/clang/test/CodeGen/systemz-inline-asm.c
@@ -123,7 +123,7 @@
long double test_f128(long double f, long double g) {
asm("axbr %0, %2" : "=f" (f) : "0" (f), "f" (g));
return f;
-// CHECK: define void @test_f128(fp128* noalias nocapture sret [[DEST:%.*]], fp128* byval nocapture readonly, fp128* byval nocapture readonly)
+// CHECK: define void @test_f128(fp128* noalias nocapture sret [[DEST:%.*]], fp128* nocapture readonly, fp128* nocapture readonly)
// CHECK: %f = load fp128* %0
// CHECK: %g = load fp128* %1
// CHECK: [[RESULT:%.*]] = tail call fp128 asm "axbr $0, $2", "=f,0,f"(fp128 %f, fp128 %g)