fix crash

Author: AlexMaclean

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -585,29 +585,31 @@ static Value *foldSelectICmpMinMax(const ICmpInst *Cmp, Value *TVal,
     Pred = CmpInst::getSwappedPredicate(Pred);
   }
 
-  if (CmpLHS == TVal) {
+  // TODO: consider handeling 'or disjoint' as well, though these would need to
+  // be converted to 'add' instructions.
+  if (CmpLHS == TVal && isa<Instruction>(FVal)) {
     if (Pred == CmpInst::ICMP_SGT &&
-        match(FVal, m_NSWAddLike(m_Specific(CmpRHS), m_One()))) {
+        match(FVal, m_NSWAdd(m_Specific(CmpRHS), m_One()))) {
       cast<Instruction>(FVal)->setHasNoUnsignedWrap(false);
       return Builder.CreateBinaryIntrinsic(Intrinsic::smax, TVal, FVal);
     }
 
     if (Pred == CmpInst::ICMP_SLT &&
-        match(FVal, m_NSWAddLike(m_Specific(CmpRHS), m_AllOnes()))) {
+        match(FVal, m_NSWAdd(m_Specific(CmpRHS), m_AllOnes()))) {
       cast<Instruction>(FVal)->setHasNoUnsignedWrap(false);
       return Builder.CreateBinaryIntrinsic(Intrinsic::smin, TVal, FVal);
     }
 
     if (Pred == CmpInst::ICMP_UGT &&
-        match(FVal, m_NUWAddLike(m_Specific(CmpRHS), m_One()))) {
+        match(FVal, m_NUWAdd(m_Specific(CmpRHS), m_One()))) {
       cast<Instruction>(FVal)->setHasNoSignedWrap(false);
       return Builder.CreateBinaryIntrinsic(Intrinsic::umax, TVal, FVal);
     }
 
     // Note: We must use isKnownNonZero here because "sub nuw %x, 1" will be
     // canonicalize to "add %x, -1" discarding the nuw flag.
     if (Pred == CmpInst::ICMP_ULT &&
-        match(FVal, m_AddLike(m_Specific(CmpRHS), m_AllOnes())) &&
+        match(FVal, m_Add(m_Specific(CmpRHS), m_AllOnes())) &&
         isKnownNonZero(CmpRHS, SQ)) {
       cast<Instruction>(FVal)->setHasNoSignedWrap(false);
       return Builder.CreateBinaryIntrinsic(Intrinsic::umin, TVal, FVal);

llvm/test/Transforms/InstCombine/minmax-fold.ll

@@ -1791,3 +1791,54 @@ define i32 @test_umin_sub1_nuw_drop_flags(i32 %x, i32 range(i32 1, 0) %w) {
   %r = select i1 %cmp, i32 %x, i32 %sub
   ret i32 %r
 }
+
+;; Confirm we don't crash on these cases.
+define i32 @test_smin_or_neg1_nsw(i32 %x, i32 %w) {
+; CHECK-LABEL: @test_smin_or_neg1_nsw(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], [[W:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP]], i32 [[X]], i32 -1
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %cmp = icmp slt i32 %x, %w
+  %sub = or disjoint i32 %w, -1
+  %r = select i1 %cmp, i32 %x, i32 %sub
+  ret i32 %r
+}
+
+define i32 @test_smax_or_1_nsw(i32 %x, i32 %w) {
+; CHECK-LABEL: @test_smax_or_1_nsw(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], [[W:%.*]]
+; CHECK-NEXT:    [[ADD:%.*]] = or disjoint i32 [[W]], 1
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[ADD]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %cmp = icmp sgt i32 %x, %w
+  %add = or disjoint i32 %w, 1
+  %r = select i1 %cmp, i32 %x, i32 %add
+  ret i32 %r
+}
+
+define i32 @test_umax_or_1_nuw(i32 %x, i32 %w) {
+; CHECK-LABEL: @test_umax_or_1_nuw(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[X:%.*]], [[W:%.*]]
+; CHECK-NEXT:    [[ADD:%.*]] = or disjoint i32 [[W]], 1
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[ADD]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %cmp = icmp ugt i32 %x, %w
+  %add = or disjoint i32 %w, 1
+  %r = select i1 %cmp, i32 %x, i32 %add
+  ret i32 %r
+}
+
+define i32 @test_umin_or_neg1_nuw(i32 %x, i32 range(i32 1, 0) %w) {
+; CHECK-LABEL: @test_umin_or_neg1_nuw(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[X:%.*]], [[W:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[CMP]], i32 [[X]], i32 -1
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %cmp = icmp ult i32 %x, %w
+  %sub = or disjoint i32 %w, -1
+  %r = select i1 %cmp, i32 %x, i32 %sub
+  ret i32 %r
+}