[llvm] r300758 - [APInt] Cast calls to add/sub/mul overflow methods to void if only their overflow bool out param is used.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Wed Apr 19 16:09:45 2017
New Revision: 300758

URL: http://llvm.org/viewvc/llvm-project?rev=300758&view=rev
Log:
[APInt] Cast calls to add/sub/mul overflow methods to void if only their overflow bool out param is used.

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.


Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/lib/Analysis/ValueTracking.cpp
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=300758&r1=300757&r2=300758&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Wed Apr 19 16:09:45 2017
@@ -1081,7 +1081,7 @@ static Value *SimplifyDiv(Instruction::B
   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());
   }

Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=300758&r1=300757&r2=300758&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Wed Apr 19 16:09:45 2017
@@ -3558,14 +3558,14 @@ OverflowResult llvm::computeOverflowForU
   // 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;
 

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=300758&r1=300757&r2=300758&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Wed Apr 19 16:09:45 2017
@@ -2833,7 +2833,7 @@ SelectionDAG::OverflowKind SelectionDAG:
     computeKnownBits(N0, N0Zero, N0One);
 
     bool overflow;
-    (~N0Zero).uadd_ov(~N1Zero, overflow);
+    (void)(~N0Zero).uadd_ov(~N1Zero, overflow);
     if (!overflow)
       return OFK_Never;
   }

Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=300758&r1=300757&r2=300758&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Wed Apr 19 16:09:45 2017
@@ -148,9 +148,9 @@ static bool MaintainNoSignedWrap(BinaryO
 
   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;
 }