Fix x86 fast-isel's cmp+branch folding to avoid folding when the

comparison is in a different basic block from the branch. In such
cases, the comparison's operands may not have initialized virtual
registers available.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111709 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/test/CodeGen/X86/fast-isel-cmp-branch.ll b/test/CodeGen/X86/fast-isel-cmp-branch.ll
new file mode 100644
index 0000000000..4ab1bc61c7
--- /dev/null
+++ b/test/CodeGen/X86/fast-isel-cmp-branch.ll
@@ -0,0 +1,29 @@
+; RUN: llc -O0 -march=x86-64 -asm-verbose=false < %s | FileCheck %s
+; rdar://8337108
+
+; Fast-isel shouldn't try to look through the compare because it's in a
+; different basic block, so its operands aren't necessarily exported
+; for cross-block usage.
+
+; CHECK: movb    %al, 7(%rsp)
+; CHECK: callq   {{_?}}bar
+; CHECK: movb    7(%rsp), %al
+
+declare void @bar()
+
+define void @foo(i32 %a, i32 %b) nounwind {
+entry:
+  %q = add i32 %a, 7
+  %r = add i32 %b, 9
+  %t = icmp ult i32 %q, %r
+  invoke void @bar() to label %next unwind label %unw
+next:
+  br i1 %t, label %true, label %return
+true:
+  call void @bar()
+  br label %return
+return:
+  ret void
+unw:
+  unreachable
+}