Teach InstructionSimplify how to look through PHI nodes. Since PHI

nodes can be used in loops, this could result in infinite looping
if there is no recursion limit, so add such a limit.  It is also
used for the SelectInst case because in theory there could be an
infinite loop there too if the basic block is unreachable.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118694 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 47 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/select.ll b/test/Transforms/InstCombine/select.ll
index c49c713..62f0eda 100644
--- a/test/Transforms/InstCombine/select.ll
+++ b/test/Transforms/InstCombine/select.ll
@@ -499,3 +499,50 @@ define i1 @test40(i1 %cond) {
 ; CHECK: @test40
 ; CHECK: ret i1 false
 }
+
+define i1 @test41(i1 %cond) {
+  %zero = alloca i32
+  %one = alloca i32
+  br i1 %cond, label %true, label %false
+true:
+  br label %ret
+false:
+  br label %ret
+ret:
+  %ptr = phi i32* [ %zero, %true ] , [ %one, %false ]
+  %isnull = icmp eq i32* %ptr, null
+  ret i1 %isnull
+; CHECK: @test41
+; CHECK: ret i1 false
+}
+
+define i1 @test42(i1 %cond, double %x) {
+  br i1 %cond, label %true, label %false
+true:
+  br label %ret
+false:
+  br label %ret
+ret:
+  %p = phi double [ %x, %true ], [ 0x7FF0000000000000, %false ]; RHS = +infty
+  %cmp = fcmp ule double %x, %p
+  ret i1 %cmp
+; CHECK: @test42
+; CHECK: ret i1 true
+}
+
+define i1 @test43(i1 %cond) {
+  %a = alloca i32
+  %b = alloca i32
+  %c = alloca i32
+  br i1 %cond, label %true, label %false
+true:
+  br label %ret
+false:
+  br label %ret
+ret:
+  %p = phi i32* [ %a, %true ], [ %b, %false ]
+  %r = icmp eq i32* %p, %c
+  ret i1 %r
+; CHECK: @test43
+; CHECK: ret i1 false
+}