[SCCP] Remove code in visitBinaryOperator (and add tests).

We visit and/or, we try to derive a lattice value for the
instruction even if one of the operands is overdefined.
If the non-overdefined value is still 'unknown' just return and wait
for ResolvedUndefsIn to "plug in" the correct value. This simplifies
the logic a bit. While I'm here add tests for missing cases.

llvm-svn: 287709

2 files changed, 29 insertions, 15 deletions

diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index eeb36bb56a1..9de3059dadf 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -928,25 +928,17 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
       NonOverdefVal = &V2State;
 
     if (NonOverdefVal) {
-      if (NonOverdefVal->isUnknown()) {
-        // Could annihilate value.
-        if (I.getOpcode() == Instruction::And)
-          markConstant(IV, &I, Constant::getNullValue(I.getType()));
-        else if (VectorType *PT = dyn_cast<VectorType>(I.getType()))
-          markConstant(IV, &I, Constant::getAllOnesValue(PT));
-        else
-          markConstant(IV, &I,
-                       Constant::getAllOnesValue(I.getType()));
+      if (NonOverdefVal->isUnknown())
         return;
-      }
 
       if (I.getOpcode() == Instruction::And) {
         // X and 0 = 0
         if (NonOverdefVal->getConstant()->isNullValue())
           return markConstant(IV, &I, NonOverdefVal->getConstant());
       } else {
+        // X or -1 = -1
         if (ConstantInt *CI = NonOverdefVal->getConstantInt())
-          if (CI->isAllOnesValue())     // X or -1 = -1
+          if (CI->isAllOnesValue())
             return markConstant(IV, &I, NonOverdefVal->getConstant());
       }
     }
diff --git a/llvm/test/Transforms/SCCP/logical-nuke.ll b/llvm/test/Transforms/SCCP/logical-nuke.ll
index 45f6f44a0eb..4ef52a25539 100644
--- a/llvm/test/Transforms/SCCP/logical-nuke.ll
+++ b/llvm/test/Transforms/SCCP/logical-nuke.ll
@@ -1,9 +1,31 @@
-; RUN: opt < %s -sccp -S | grep "ret i32 0"
+; RUN: opt < %s -sccp -S | FileCheck %s
 
 ; Test that SCCP has basic knowledge of when and/or nuke overdefined values.
 
-define i32 @test(i32 %X) {
-	%Y = and i32 %X, 0		; <i32> [#uses=1]
-	ret i32 %Y
+; CHECK-LABEL: test
+; CHECK: ret i32 0
+ define i32 @test(i32 %X) {
+  %Y = and i32 %X, 0
+  ret i32 %Y
 }
 
+; CHECK-LABEL: test2
+; CHECK: ret i32 -1
+define i32 @test2(i32 %X) {
+  %Y = or i32 -1, %X
+  ret i32 %Y
+}
+
+; CHECK-LABEL: test3
+; CHECK: ret i32 0
+define i32 @test3(i32 %X) {
+  %Y = and i32 undef, %X
+  ret i32 %Y
+}
+
+; CHECK-LABEL: test4
+; CHECK: ret i32 -1
+define i32 @test4(i32 %X) {
+  %Y = or i32 %X, undef
+  ret i32 %Y
+}