A bunch of misc fixes to SCCPSolver::ResolvedUndefsIn, including a fix to stop

making random bad assumptions about instructions which are not explicitly listed.  

Includes fix for rdar://9956541, a version of "undef ^ undef should return
0 because it's easier than arguing with users".

llvm-svn: 137777

1 files changed, 57 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SCCP/undef-resolve.ll b/llvm/test/Transforms/SCCP/undef-resolve.ll
index bed561c8e4f..e947d79ab65 100644
--- a/llvm/test/Transforms/SCCP/undef-resolve.ll
+++ b/llvm/test/Transforms/SCCP/undef-resolve.ll
@@ -104,3 +104,60 @@ bb1.us-lcssa:                                     ; preds = %control
 bb1:                                              ; preds = %bb1.us-lcssa, %bb1.us-lcssa.us
   ret i32 0
 }
+
+; Make sure SCCP honors the xor "idiom"
+; rdar://9956541
+define i32 @test3() {
+  %t = xor i32 undef, undef
+  ret i32 %t
+; CHECK: @test3
+; CHECK: ret i32 0
+}
+
+; Be conservative with FP ops
+define double @test4(double %x) {
+  %t = fadd double %x, undef
+  ret double %t
+; CHECK: @test4
+; CHECK: fadd double %x, undef
+}
+
+; Make sure casts produce a possible value
+define i32 @test5() {
+  %t = sext i8 undef to i32
+  ret i32 %t
+; CHECK: @test5
+; CHECK: ret i32 0
+}
+
+; Make sure ashr produces a possible value
+define i32 @test6() {
+  %t = ashr i32 undef, 31
+  ret i32 %t
+; CHECK: @test6
+; CHECK: ret i32 -1
+}
+
+; Make sure lshr produces a possible value
+define i32 @test7() {
+  %t = lshr i32 undef, 31
+  ret i32 %t
+; CHECK: @test7
+; CHECK: ret i32 0
+}
+
+; icmp eq with undef simplifies to undef
+define i1 @test8() {
+  %t = icmp eq i32 undef, -1
+  ret i1 %t
+; CHECK: @test8
+; CHECK: ret i1 undef
+}
+
+; Make sure we don't conclude that relational comparisons simplify to undef
+define i1 @test9() {
+  %t = icmp ugt i32 undef, -1
+  ret i1 %t
+; CHECK: @test9
+; CHECK: icmp ugt
+}