[InstCombine] Add constant splat handling to one of the ICMP_SLT/SGT cases in foldICmpUsingKnownBits.

llvm-svn: 314025

2 files changed, 44 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index cd59366d5ee..a9911f42cba 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4247,10 +4247,10 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
       return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
     if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
       return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
-      if (Op1Max == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C
+    if (Op1Min == Op1Max) { // Constant RHS
+      if (Op1Min == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C
         return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            Builder.getInt(CI->getValue() - 1));
+                            ConstantInt::get(Op1->getType(), Op1Min - 1));
     }
     break;
   case ICmpInst::ICMP_SGT:
@@ -4258,13 +4258,12 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
       return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
     if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
       return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-
     if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
       return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+    if (Op1Min == Op1Max) { // Constant RHS
       if (Op1Min == Op0Max - 1) // A >s C -> A == C+1 if max(A)-1 == C
         return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            Builder.getInt(CI->getValue() + 1));
+                            ConstantInt::get(Op1->getType(), Op1Min + 1));
     }
     break;
   case ICmpInst::ICMP_SGE:
diff --git a/llvm/test/Transforms/InstCombine/icmp-add.ll b/llvm/test/Transforms/InstCombine/icmp-add.ll
index efeb9d5bb45..c9e13717f29 100644
--- a/llvm/test/Transforms/InstCombine/icmp-add.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -96,6 +96,16 @@ define i1 @nsw_slt1(i8 %a) {
   ret i1 %c
 }
 
+define <2 x i1> @nsw_slt1_splat_vec(<2 x i8> %a) {
+; CHECK-LABEL: @nsw_slt1_splat_vec(
+; CHECK-NEXT:    [[C:%.*]] = icmp eq <2 x i8> [[A:%.*]], <i8 -128, i8 -128>
+; CHECK-NEXT:    ret <2 x i1> [[C]]
+;
+  %b = add nsw <2 x i8> %a, <i8 100, i8 100>
+  %c = icmp slt <2 x i8> %b, <i8 -27, i8 -27>
+  ret <2 x i1> %c
+}
+
 ; icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2), when C - C2 does not overflow.
 ; This becomes equality because it's at the limit.
 
@@ -109,6 +119,16 @@ define i1 @nsw_slt2(i8 %a) {
   ret i1 %c
 }
 
+define <2 x i1> @nsw_slt2_splat_vec(<2 x i8> %a) {
+; CHECK-LABEL: @nsw_slt2_splat_vec(
+; CHECK-NEXT:    [[C:%.*]] = icmp ne <2 x i8> [[A:%.*]], <i8 127, i8 127>
+; CHECK-NEXT:    ret <2 x i1> [[C]]
+;
+  %b = add nsw <2 x i8> %a, <i8 -100, i8 -100>
+  %c = icmp slt <2 x i8> %b, <i8 27, i8 27>
+  ret <2 x i1> %c
+}
+
 ; icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2), when C - C2 does not overflow.
 ; Less than the limit, so the predicate doesn't change.
 
@@ -148,9 +168,26 @@ define i1 @nsw_sgt1(i8 %a) {
   ret i1 %c
 }
 
-; icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2), when C - C2 does not overflow.
-; Try a vector type to make sure that works too.
 ; FIXME: This should be 'eq 127' as above.
+define <2 x i1> @nsw_sgt1_splat_vec(<2 x i8> %a) {
+; CHECK-LABEL: @nsw_sgt1_splat_vec(
+; CHECK-NEXT:    [[C:%.*]] = icmp eq <2 x i8> [[A:%.*]], <i8 127, i8 127>
+; CHECK-NEXT:    ret <2 x i1> [[C]]
+;
+  %b = add nsw <2 x i8> %a, <i8 -100, i8 -100>
+  %c = icmp sgt <2 x i8> %b, <i8 26, i8 26>
+  ret <2 x i1> %c
+}
+
+define i1 @nsw_sgt2(i8 %a) {
+; CHECK-LABEL: @nsw_sgt2(
+; CHECK-NEXT:    [[C:%.*]] = icmp sgt i8 [[A:%.*]], -126
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %b = add nsw i8 %a, 100
+  %c = icmp sgt i8 %b, -26
+  ret i1 %c
+}
 
 define <2 x i1> @nsw_sgt2_splat_vec(<2 x i8> %a) {
 ; CHECK-LABEL: @nsw_sgt2_splat_vec(