[llvm] [RISCV][GISel] Legalize G_SMULO/G_UMULO (PR #67635)

[Amara Emerson via llvm-commits]

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@@ -145,13 +145,31 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
         .legalFor({XLenLLT})
         .lower();
     // clang-format on
+
+    getActionDefinitionsBuilder({G_SMULO, G_UMULO})
+        .minScalar(0, XLenLLT)
+        .lower();
   } else {
     getActionDefinitionsBuilder(G_MUL)
         .libcallFor({XLenLLT, DoubleXLenLLT})
         .widenScalarToNextPow2(0)
         .clampScalar(0, XLenLLT, DoubleXLenLLT);
 
     getActionDefinitionsBuilder({G_SMULH, G_UMULH}).lowerFor({XLenLLT});
+
+    getActionDefinitionsBuilder({G_SMULO, G_UMULO})
+        .minScalar(0, XLenLLT)
+        // Widen XLenLLT to DoubleXLenLLT so we can use a single libcall to get
+        // the low bits for the mul result and high bits to do the overflow
+        // check.
+        .widenScalarIf(
+            [=, &ST](const LegalityQuery &Query) {
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aemerson wrote:

No need for `ST`?

https://github.com/llvm/llvm-project/pull/67635