[APInt] Cast calls to add/sub/mul overflow methods to void if only their overflow...

This is preparation for a clang change to improve the [[nodiscard]] warning to not be ignored on methods that return a class marked [[nodiscard]] that are defined in the class itself. See D32207.

We should consider adding wrapper methods to APInt that return the overflow flag directly and discard the APInt result. This would eliminate the void casts and the need to create a bool before the call to pass to the out param.

llvm-svn: 300758

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 70abc07f0110a0cf07eaefcdd8e207baeb17d224..bca3435863e5d7b329b324f19dc796483ac49539 100644 (file)
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1081,7 +1081,7 @@ static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
   if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
       match(Op1, m_ConstantInt(C2))) {
     bool Overflow;
-    C1->getValue().umul_ov(C2->getValue(), Overflow);
+    (void)C1->getValue().umul_ov(C2->getValue(), Overflow);
     if (Overflow)
       return Constant::getNullValue(Op0->getType());
   }

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 974ec02598f3646024de8d5ebc80665d3e3ff9dc..0bbb37295f1080ca43c3f8a83a5b7b436b1f8617 100644 (file)
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3558,14 +3558,14 @@ OverflowResult llvm::computeOverflowForUnsignedMul(const Value *LHS,
   // We know the multiply operation doesn't overflow if the maximum values for
   // each operand will not overflow after we multiply them together.
   bool MaxOverflow;
-  LHSMax.umul_ov(RHSMax, MaxOverflow);
+  (void)LHSMax.umul_ov(RHSMax, MaxOverflow);
   if (!MaxOverflow)
     return OverflowResult::NeverOverflows;
 
   // We know it always overflows if multiplying the smallest possible values for
   // the operands also results in overflow.
   bool MinOverflow;
-  LHSKnownOne.umul_ov(RHSKnownOne, MinOverflow);
+  (void)LHSKnownOne.umul_ov(RHSKnownOne, MinOverflow);
   if (MinOverflow)
     return OverflowResult::AlwaysOverflows;
 

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 8c677d901e44c1b55f0e8372a49d1313d8c09545..c41d62716f24d24a623b917efc4f17dedbd58c13 100644 (file)
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2833,7 +2833,7 @@ SelectionDAG::OverflowKind SelectionDAG::computeOverflowKind(SDValue N0,
     computeKnownBits(N0, N0Zero, N0One);
 
     bool overflow;
-    (~N0Zero).uadd_ov(~N1Zero, overflow);
+    (void)(~N0Zero).uadd_ov(~N1Zero, overflow);
     if (!overflow)
       return OFK_Never;
   }

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 88ef17bbc8fa6f9591cdc238861483327f377139..81f2d9fa179f9f5183b7943e1d438380783009c3 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -148,9 +148,9 @@ static bool MaintainNoSignedWrap(BinaryOperator &I, Value *B, Value *C) {
 
   bool Overflow = false;
   if (Opcode == Instruction::Add)
-    BVal->sadd_ov(*CVal, Overflow);
+    (void)BVal->sadd_ov(*CVal, Overflow);
   else
-    BVal->ssub_ov(*CVal, Overflow);
+    (void)BVal->ssub_ov(*CVal, Overflow);
 
   return !Overflow;
 }