[llvm] [InstCombine] Simplify with.overflow intrinsics with assumption information (PR #84016)

[Andreas Jonson via llvm-commits]

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@@ -818,6 +818,33 @@ InstCombinerImpl::foldIntrinsicWithOverflowCommon(IntrinsicInst *II) {
   if (OptimizeOverflowCheck(WO->getBinaryOp(), WO->isSigned(), WO->getLHS(),
                             WO->getRHS(), *WO, OperationResult, OverflowResult))
     return createOverflowTuple(WO, OperationResult, OverflowResult);
+
+  // See whether we can optimize the overflow check with assumption information.
+  for (User *U : WO->users()) {
+    if (!match(U, m_ExtractValue<1>(m_Value())))
+      continue;
+
+    for (auto &AssumeVH : AC.assumptionsFor(U)) {
+      if (!AssumeVH)
+        continue;
+      CallInst *I = cast<CallInst>(AssumeVH);
+      if (!match(I->getArgOperand(0), m_Not(m_Specific(U))))
+        continue;
+      if (!isValidAssumeForContext(I, II, &DT))
+        continue;
+      Value *Result =
+          Builder.CreateBinOp(WO->getBinaryOp(), WO->getLHS(), WO->getRHS());
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andjo403 wrote:

OptimizeOverflowCheck also take the name of the WO instruction shall it be done here also?

https://github.com/llvm/llvm-project/pull/84016