Stackmap shadows should consider call returns a branch target.
To avoid emitting too many nops, a stackmap shadow can include emitted instructions in the shadow, but these must not include branch targets.
A return from a call should count as a branch target as patching over the instructions after the call would lead to incorrect behaviour for threads currently making that call, when they return.
llvm-svn: 220710
diff --git a/llvm/test/CodeGen/X86/stackmap-shadow-optimization.ll b/llvm/test/CodeGen/X86/stackmap-shadow-optimization.ll
index 6f7c593..f640b9e 100644
--- a/llvm/test/CodeGen/X86/stackmap-shadow-optimization.ll
+++ b/llvm/test/CodeGen/X86/stackmap-shadow-optimization.ll
@@ -1,16 +1,18 @@
; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=corei7 | FileCheck %s
-; Check that the X86 stackmap shadow optimization is only outputting a 1-byte
-; nop here. 8-bytes are requested, but 7 are covered by the code for the call to
-; bar, the frame teardown and the return.
+; Check that the X86 stackmap shadow optimization is only outputting a 3-byte
+; nop here. 8-bytes are requested, but 5 are covered by the code for the call to
+; bar. However, the frame teardown and the return do not count towards the
+; stackmap shadow as the call return counts as a branch target so must flush
+; the shadow.
define void @shadow_optimization_test() {
entry:
; CHECK-LABEL: shadow_optimization_test:
; CHECK: callq _bar
; CHECK-NOT: nop
; CHECK: callq _bar
-; CHECK: retq
; CHECK: nop
+; CHECK: retq
call void @bar()
tail call void (i64, i32, ...)* @llvm.experimental.stackmap(i64 0, i32 8)
call void @bar()