[llvm] Add out-of-line-atomics support to GlobalISel (PR #74588)

[Pavel Iliin via llvm-commits]

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@@ -757,17 +757,35 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
       .lowerIf(
           all(typeInSet(0, {s8, s16, s32, s64, s128}), typeIs(2, p0)));
 
+  LegalityPredicate UseOutlineAtomics = [&ST](const LegalityQuery &Query) {
+    return ST.outlineAtomics() && !ST.hasLSE();
+  };
+
   getActionDefinitionsBuilder(G_ATOMIC_CMPXCHG)
-      .customIf([](const LegalityQuery &Query) {
-        return Query.Types[0].getSizeInBits() == 128;
-      })
-      .clampScalar(0, s32, s64)
-      .legalIf(all(typeInSet(0, {s32, s64}), typeIs(1, p0)));
+      .legalIf(all(typeInSet(0, {s32, s64}), typeIs(1, p0),
+                   predNot(UseOutlineAtomics)))
+      .customIf(all(typeIs(0, s128), predNot(UseOutlineAtomics)))
+      .libcallIf(all(typeInSet(0, {s8, s16, s32, s64, s128}), typeIs(1, p0),
+                     UseOutlineAtomics))
+      .clampScalar(0, s32, s64);
+
+  getActionDefinitionsBuilder({G_ATOMICRMW_XCHG, G_ATOMICRMW_ADD,
+                               G_ATOMICRMW_SUB, G_ATOMICRMW_AND, G_ATOMICRMW_OR,
+                               G_ATOMICRMW_XOR})
+      .legalIf(all(typeInSet(0, {s32, s64}), typeIs(1, p0),
+                   predNot(UseOutlineAtomics)))
+      .libcallIf(all(typeInSet(0, {s8, s16, s32, s64}), typeIs(1, p0),
+                     UseOutlineAtomics))
+      .clampScalar(0, s32, s64);
 
+  // [U]Min/[U]Max RWM atomics are used in __sync_fetch_ libcalls so far.
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ilinpv wrote:

Maybe put here short summary with link to AArch64ISelLowering.cpp comment and keep details there. Eventually we should support min/max atomics in both isel and global-isel.

https://github.com/llvm/llvm-project/pull/74588