[llvm] [ValueTracking][X86] Compute KnownBits for phadd/phsub (PR #92429)

[Simon Pilgrim via llvm-commits]

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@@ -1725,6 +1752,56 @@ static void computeKnownBitsFromOperator(const Operator *I,
       case Intrinsic::x86_sse42_crc32_64_64:
         Known.Zero.setBitsFrom(32);
         break;
+      case Intrinsic::x86_ssse3_phadd_d:
+      case Intrinsic::x86_ssse3_phadd_w:
+      case Intrinsic::x86_ssse3_phadd_d_128:
+      case Intrinsic::x86_ssse3_phadd_w_128:
+      case Intrinsic::x86_avx2_phadd_d:
+      case Intrinsic::x86_avx2_phadd_w: {
+        Known = computeKnownBitsForHorizontalOperation(
+            I, DemandedElts, Depth, Q,
+            [](const KnownBits &KnownLHS, const KnownBits &KnownRHS) {
+              return KnownBits::computeForAddSub(/*Add=*/true, /*NSW=*/false,
+                                                 /*NUW=*/false, KnownLHS,
+                                                 KnownRHS);
+            });
+        break;
+      }
+      case Intrinsic::x86_ssse3_phadd_sw:
+      case Intrinsic::x86_ssse3_phadd_sw_128:
+      case Intrinsic::x86_avx2_phadd_sw: {
+        Known = computeKnownBitsForHorizontalOperation(
+            I, DemandedElts, Depth, Q,
+            [](const KnownBits &KnownLHS, const KnownBits &KnownRHS) {
+              return KnownBits::sadd_sat(KnownLHS, KnownRHS);
+            });
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RKSimon wrote:

Can't you just use KnownBits::sadd_sat without the lambda wrapper?

https://github.com/llvm/llvm-project/pull/92429