[llvm] [AArch64][GlobalISel] Basic add_sat and sub_sat vector handling. (PR #80650)

[David Green via llvm-commits]

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@@ -1153,8 +1150,14 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
       .minScalarEltSameAsIf(always, 1, 0)
       .maxScalarEltSameAsIf(always, 1, 0);
 
-  // TODO: Vector types.
-  getActionDefinitionsBuilder({G_SADDSAT, G_SSUBSAT}).lowerIf(isScalar(0));
+  getActionDefinitionsBuilder({G_UADDSAT, G_SADDSAT, G_USUBSAT, G_SSUBSAT})
+      .legalFor({v2s64, v2s32, v4s32, v4s16, v8s16, v8s8, v16s8})
+      .clampNumElements(0, v8s8, v16s8)
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davemgreen wrote:

We want to lower scalar as opposed to widen, I believe, although they might lead to similar result in the end. For vector types it is more unclear at the moment, but they might want to lower too.

https://github.com/llvm/llvm-project/pull/80650