Teach jump threading to duplicate small blocks when the branch
condition is a xor with a phi node. This eliminates nonsense
like this from 176.gcc in several places:
LBB166_84:
testl %eax, %eax
- setne %al
- xorb %cl, %al
- notb %al
- testb $1, %al
- je LBB166_85
+ je LBB166_69
+ jmp LBB166_85
This is rdar://7391699
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93221 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/JumpThreading/basic.ll b/test/Transforms/JumpThreading/basic.ll
index ac31cdb..34b4243 100644
--- a/test/Transforms/JumpThreading/basic.ll
+++ b/test/Transforms/JumpThreading/basic.ll
@@ -383,11 +383,11 @@
}
-;;; Duplicate condition to avoid xor of cond.
-;;; TODO: Make this happen.
-define i32 @testXX(i1 %cond, i1 %cond2) {
+;; Duplicate condition to avoid xor of cond.
+;; rdar://7391699
+define i32 @test13(i1 %cond, i1 %cond2) {
Entry:
-; CHECK: @testXX
+; CHECK: @test13
%v1 = call i32 @f1()
br i1 %cond, label %Merge, label %F1
@@ -396,7 +396,8 @@
Merge:
%B = phi i1 [true, %Entry], [%cond2, %F1]
- %M = icmp eq i32 %v1, 192
+ %C = phi i32 [192, %Entry], [%v1, %F1]
+ %M = icmp eq i32 %C, 192
%N = xor i1 %B, %M
br i1 %N, label %T2, label %F2
@@ -405,6 +406,18 @@
F2:
ret i32 %v1
+
+;; FIXME: CONSTANT FOLD on clone and when phi gets eliminated.
+
+; CHECK: Entry.Merge_crit_edge:
+; CHECK-NEXT: %M1 = icmp eq i32 192, 192
+; CHECK-NEXT: %N2 = xor i1 true, %M1
+; CHECK-NEXT: br i1 %N2, label %T2, label %F2
+
+; CHECK: Merge:
+; CHECK-NEXT: %M = icmp eq i32 %v1, 192
+; CHECK-NEXT: %N = xor i1 %cond2, %M
+; CHECK-NEXT: br i1 %N, label %T2, label %F2
}