[ShrinkWrap] Fix FindIDom to only have one kind of failure.
FindIDom() can fail in two different ways - it can either return nullptr or the
block itself, depending on the circumstances. Some users of FindIDom() check
one error condition, while others check the other.
Change it to always return nullptr on failure.
This fixes PR26004.
Differential Revision: http://reviews.llvm.org/D15847
llvm-svn: 256955
diff --git a/llvm/test/CodeGen/X86/shrinkwrap-hang.ll b/llvm/test/CodeGen/X86/shrinkwrap-hang.ll
new file mode 100644
index 0000000..e1e4eef
--- /dev/null
+++ b/llvm/test/CodeGen/X86/shrinkwrap-hang.ll
@@ -0,0 +1,32 @@
+; RUN: llc %s -o - -enable-shrink-wrap=true | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
+target triple = "i686-pc-linux"
+
+@b = global i32 1, align 4
+@a = common global i32 0, align 4
+
+declare void @fn1() #0
+
+; CHECK-LABEL: fn2:
+define void @fn2() #0 {
+entry:
+ %0 = load i32, i32* @b, align 4
+ %tobool = icmp eq i32 %0, 0
+ br i1 %tobool, label %if.end, label %lbl
+
+lbl: ; preds = %if.end, %entry
+ store i32 0, i32* @b, align 4
+ br label %if.end
+
+if.end: ; preds = %entry, %lbl
+ tail call void @fn1()
+ %1 = load i32, i32* @b, align 4
+ %tobool1 = icmp eq i32 %1, 0
+ br i1 %tobool1, label %if.end3, label %lbl
+
+if.end3: ; preds = %if.end
+ ret void
+}
+
+attributes #0 = { norecurse nounwind "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="pentium4" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }