[llvm] IC: teach foldSelectOpOp about samesign (PR #122723)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Ramkumar Ramachandra (artagnon)

<details>
<summary>Changes</summary>

Follow up on 4a0d53a (PatternMatch: migrate to CmpPredicate) to get rid of one of the FIXMEs it introduced by replacing a predicate comparison with CmpPredicate::getMatching.

---
Full diff: https://github.com/llvm/llvm-project/pull/122723.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp (+4-4) 
- (modified) llvm/test/Transforms/InstCombine/select-cmp.ll (+96) 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index f66a976ccb47fe..d5d9a829c3068a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -428,10 +428,10 @@ Instruction *InstCombinerImpl::foldSelectOpOp(SelectInst &SI, Instruction *TI,
     CmpPredicate TPred, FPred;
     if (match(TI, m_ICmp(TPred, m_Value(), m_Value())) &&
         match(FI, m_ICmp(FPred, m_Value(), m_Value()))) {
-      // FIXME: Use CmpPredicate::getMatching here.
-      CmpInst::Predicate T = TPred, F = FPred;
-      if (T == F || T == ICmpInst::getSwappedCmpPredicate(F)) {
-        bool Swapped = T != F;
+      bool Swapped = ICmpInst::isRelational(FPred) &&
+                     CmpPredicate::getMatching(
+                         TPred, ICmpInst::getSwappedCmpPredicate(FPred));
+      if (CmpPredicate::getMatching(TPred, FPred) || Swapped) {
         if (Value *MatchOp =
                 getCommonOp(TI, FI, ICmpInst::isEquality(TPred), Swapped)) {
           Value *NewSel = Builder.CreateSelect(Cond, OtherOpT, OtherOpF,
diff --git a/llvm/test/Transforms/InstCombine/select-cmp.ll b/llvm/test/Transforms/InstCombine/select-cmp.ll
index f7505bd85f89eb..7e5d5821d9f6a7 100644
--- a/llvm/test/Transforms/InstCombine/select-cmp.ll
+++ b/llvm/test/Transforms/InstCombine/select-cmp.ll
@@ -23,6 +23,18 @@ define i1 @icmp_ne_common_op00(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_ne_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_ne_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp samesign ne i6 %x, %y
+  %cmp2 = icmp ne i6 %x, %z
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_ne_common_op01(i1 %c, i3 %x, i3 %y, i3 %z) {
 ; CHECK-LABEL: @icmp_ne_common_op01(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i3 [[Y:%.*]], i3 [[Z:%.*]]
@@ -71,6 +83,18 @@ define i1 @icmp_eq_common_op00(i1 %c, i5 %x, i5 %y, i5 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_eq_samesign_common(i1 %c, i5 %x, i5 %y, i5 %z) {
+; CHECK-LABEL: @icmp_eq_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i5 [[Y:%.*]], i5 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i5 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp eq i5 %x, %y
+  %cmp2 = icmp samesign eq i5 %x, %z
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define <5 x i1> @icmp_eq_common_op01(<5 x i1> %c, <5 x i7> %x, <5 x i7> %y, <5 x i7> %z) {
 ; CHECK-LABEL: @icmp_eq_common_op01(
 ; CHECK-NEXT:    [[R_V:%.*]] = select <5 x i1> [[C:%.*]], <5 x i7> [[Y:%.*]], <5 x i7> [[Z:%.*]]
@@ -134,6 +158,18 @@ define i1 @icmp_slt_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_slt_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_slt_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp samesign ult i6 %x, %y
+  %cmp2 = icmp slt i6 %x, %z
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_sgt_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_sgt_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
@@ -146,6 +182,18 @@ define i1 @icmp_sgt_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_sgt_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_sgt_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ugt i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp samesign ugt i6 %x, %y
+  %cmp2 = icmp sgt i6 %x, %z
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_sle_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_sle_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
@@ -158,6 +206,18 @@ define i1 @icmp_sle_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_sle_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_sle_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp sge i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp sle i6 %y, %x
+  %cmp2 = icmp samesign ule i6 %z, %x
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_sge_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_sge_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
@@ -170,6 +230,18 @@ define i1 @icmp_sge_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_sge_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_sge_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp sge i6 %y, %x
+  %cmp2 = icmp samesign uge i6 %z, %x
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_slt_sgt_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_slt_sgt_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
@@ -182,6 +254,18 @@ define i1 @icmp_slt_sgt_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_slt_sgt_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_slt_sgt_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp samesign ult i6 %x, %y
+  %cmp2 = icmp sgt i6 %z, %x
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_sle_sge_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_sle_sge_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
@@ -194,6 +278,18 @@ define i1 @icmp_sle_sge_common(i1 %c, i6 %x, i6 %y, i6 %z) {
   ret i1 %r
 }
 
+define i1 @icmp_sle_sge_samesign_common(i1 %c, i6 %x, i6 %y, i6 %z) {
+; CHECK-LABEL: @icmp_sle_sge_samesign_common(
+; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp sge i6 [[X:%.*]], [[R_V]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cmp1 = icmp sle i6 %y, %x
+  %cmp2 = icmp samesign uge i6 %x, %z
+  %r = select i1 %c, i1 %cmp1, i1 %cmp2
+  ret i1 %r
+}
+
 define i1 @icmp_ult_common(i1 %c, i6 %x, i6 %y, i6 %z) {
 ; CHECK-LABEL: @icmp_ult_common(
 ; CHECK-NEXT:    [[R_V:%.*]] = select i1 [[C:%.*]], i6 [[Y:%.*]], i6 [[Z:%.*]]

``````````

</details>


https://github.com/llvm/llvm-project/pull/122723