[AArch64][GlobalISel] Mark G_BR as always legal. NFC #153545
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As far as I understand this will not affect anything, just lower the exposure to the legacy legalizer rules.
Member
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@llvm/pr-subscribers-backend-aarch64 Author: David Green (davemgreen) ChangesAs far as I understand this will not affect anything, just lower the exposure to the legacy legalizer rules. Full diff: https://github.com/llvm/llvm-project/pull/153545.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index e0e1af78770de..faae7da94d55e 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -965,6 +965,7 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
{s128, s64}});
// Control-flow
+ getActionDefinitionsBuilder(G_BR).alwaysLegal();
getActionDefinitionsBuilder(G_BRCOND)
.legalFor({s32})
.clampScalar(0, s32, s32);
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
index 5c164bf672082..49f58e3ec14fb 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -672,8 +672,8 @@
# DEBUG-NEXT: .. the first uncovered type index: 2, OK
# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
# DEBUG-NEXT: G_BR (opcode {{[0-9]+}}): 0 type indices, 0 imm indices
-# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
-# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: G_BRJT (opcode {{[0-9]+}}): 2 type indices
# DEBUG-NEXT: .. the first uncovered type index: 2, OK
# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
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Member
|
@llvm/pr-subscribers-llvm-globalisel Author: David Green (davemgreen) ChangesAs far as I understand this will not affect anything, just lower the exposure to the legacy legalizer rules. Full diff: https://github.com/llvm/llvm-project/pull/153545.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index e0e1af78770de..faae7da94d55e 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -965,6 +965,7 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
{s128, s64}});
// Control-flow
+ getActionDefinitionsBuilder(G_BR).alwaysLegal();
getActionDefinitionsBuilder(G_BRCOND)
.legalFor({s32})
.clampScalar(0, s32, s32);
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
index 5c164bf672082..49f58e3ec14fb 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -672,8 +672,8 @@
# DEBUG-NEXT: .. the first uncovered type index: 2, OK
# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
# DEBUG-NEXT: G_BR (opcode {{[0-9]+}}): 0 type indices, 0 imm indices
-# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
-# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: G_BRJT (opcode {{[0-9]+}}): 2 type indices
# DEBUG-NEXT: .. the first uncovered type index: 2, OK
# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
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arsenm
approved these changes
Aug 14, 2025
Collaborator
Author
|
I was wondering if we should be doing this universally for all targets? They should pretty much always be legal, I'm not sure if there is a good place to put that. |
Contributor
|
I would not assume these are directly legal. I think the harm of trying to have default hard-to-opt-out of rules is greater than the savings of just having a list of explicit always legal operations |
aemerson
approved these changes
Aug 15, 2025
aemerson
approved these changes
Aug 21, 2025
davemgreen
added a commit
that referenced
this pull request
Aug 23, 2025
…al. NFC Similar to #153545 these nodes are always legal for AArch64, this patch marks them so to reduce the dependency on the legacy legalizer ruleset.
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As far as I understand this will not affect anything, just lower the exposure to the legacy legalizer rules.