[PATCH] D59471: [InstCombine] Fold add nuw + uadd.with.overflow

[Dan Robertson via Phabricator via llvm-commits]

dlrobertson updated this revision to Diff 191410.
dlrobertson added a comment.

Combine `saddo` and `uaddo` branch


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59471/new/

https://reviews.llvm.org/D59471

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/uadd-with-overflow.ll


Index: llvm/test/Transforms/InstCombine/uadd-with-overflow.ll
===================================================================
--- llvm/test/Transforms/InstCombine/uadd-with-overflow.ll
+++ llvm/test/Transforms/InstCombine/uadd-with-overflow.ll
@@ -11,9 +11,8 @@
 
 define { i32, i1 } @simple_fold(i32 %x) {
 ; CHECK-LABEL: @simple_fold(
-; CHECK-NEXT:    [[A:%.*]] = add nuw i32 [[X:%.*]], 7
-; CHECK-NEXT:    [[B:%.*]] = tail call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[A]], i32 13)
-; CHECK-NEXT:    ret { i32, i1 } [[B]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[X:%.*]], i32 20)
+; CHECK-NEXT:    ret { i32, i1 } [[TMP1]]
 ;
   %a = add nuw i32 %x, 7
   %b = tail call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 %a, i32 13)
@@ -22,9 +21,8 @@
 
 define { i8, i1 } @fold_on_constant_add_no_overflow(i8 %x) {
 ; CHECK-LABEL: @fold_on_constant_add_no_overflow(
-; CHECK-NEXT:    [[A:%.*]] = add nuw i8 [[X:%.*]], -56
-; CHECK-NEXT:    [[B:%.*]] = tail call { i8, i1 } @llvm.uadd.with.overflow.i8(i8 [[A]], i8 55)
-; CHECK-NEXT:    ret { i8, i1 } [[B]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call { i8, i1 } @llvm.uadd.with.overflow.i8(i8 [[X:%.*]], i8 -1)
+; CHECK-NEXT:    ret { i8, i1 } [[TMP1]]
 ;
   %a = add nuw i8 %x, 200
   %b = tail call { i8, i1 } @llvm.uadd.with.overflow.i8(i8 %a, i8 55)
@@ -65,9 +63,8 @@
 
 define { <2 x i32>, <2 x i1> } @fold_simple_splat_constant(<2 x i32> %x) {
 ; CHECK-LABEL: @fold_simple_splat_constant(
-; CHECK-NEXT:    [[A:%.*]] = add nuw <2 x i32> [[X:%.*]], <i32 12, i32 12>
-; CHECK-NEXT:    [[B:%.*]] = tail call { <2 x i32>, <2 x i1> } @llvm.uadd.with.overflow.v2i32(<2 x i32> [[A]], <2 x i32> <i32 30, i32 30>)
-; CHECK-NEXT:    ret { <2 x i32>, <2 x i1> } [[B]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call { <2 x i32>, <2 x i1> } @llvm.uadd.with.overflow.v2i32(<2 x i32> [[X:%.*]], <2 x i32> <i32 42, i32 42>)
+; CHECK-NEXT:    ret { <2 x i32>, <2 x i1> } [[TMP1]]
 ;
   %a = add nuw <2 x i32> %x, <i32 12, i32 12>
   %b = tail call { <2 x i32>, <2 x i1> } @llvm.uadd.with.overflow.v2i32(<2 x i32> %a, <2 x i32> <i32 30, i32 30>)
@@ -98,9 +95,8 @@
 
 define { i32, i1 } @fold_nuwnsw(i32 %x) {
 ; CHECK-LABEL: @fold_nuwnsw(
-; CHECK-NEXT:    [[A:%.*]] = add nuw nsw i32 [[X:%.*]], 12
-; CHECK-NEXT:    [[B:%.*]] = tail call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[A]], i32 30)
-; CHECK-NEXT:    ret { i32, i1 } [[B]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 [[X:%.*]], i32 42)
+; CHECK-NEXT:    ret { i32, i1 } [[TMP1]]
 ;
   %a = add nuw nsw i32 %x, 12
   %b = tail call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 %a, i32 30)
Index: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2046,6 +2046,7 @@
       return &CI;
     break;
   }
+  case Intrinsic::uadd_with_overflow:
   case Intrinsic::sadd_with_overflow: {
     if (Instruction *I = canonicalizeConstantArg0ToArg1(CI))
       return I;
@@ -2053,25 +2054,27 @@
       return I;
 
     // Given 2 constant operands whose sum does not overflow:
+    // uaddo (X +nuw C0), C1 -> uaddo X, C0 + C1
     // saddo (X +nsw C0), C1 -> saddo X, C0 + C1
     Value *X;
     const APInt *C0, *C1;
     Value *Arg0 = II->getArgOperand(0);
     Value *Arg1 = II->getArgOperand(1);
-    if (match(Arg0, m_NSWAdd(m_Value(X), m_APInt(C0))) &&
-        match(Arg1, m_APInt(C1))) {
+    bool IsSigned = II->getIntrinsicID() == Intrinsic::sadd_with_overflow;
+    bool HasNWAdd = IsSigned ? match(Arg0, m_NSWAdd(m_Value(X), m_APInt(C0)))
+                             : match(Arg0, m_NUWAdd(m_Value(X), m_APInt(C0)));
+    if (HasNWAdd && match(Arg1, m_APInt(C1))) {
       bool Overflow;
-      APInt NewC = C1->sadd_ov(*C0, Overflow);
+      APInt NewC =
+          IsSigned ? C1->sadd_ov(*C0, Overflow) : C1->uadd_ov(*C0, Overflow);
       if (!Overflow)
         return replaceInstUsesWith(
             *II, Builder.CreateBinaryIntrinsic(
-                     Intrinsic::sadd_with_overflow, X,
+                     II->getIntrinsicID(), X,
                      ConstantInt::get(Arg1->getType(), NewC)));
     }
-
     break;
   }
-  case Intrinsic::uadd_with_overflow:
   case Intrinsic::umul_with_overflow:
   case Intrinsic::smul_with_overflow:
     if (Instruction *I = canonicalizeConstantArg0ToArg1(CI))


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