[llvm] [GISel][Legalizer] Rework `changeElementCountTo` (NFC) (PR #158617)

[via llvm-commits]

https://github.com/DenisGZM created https://github.com/llvm/llvm-project/pull/158617

Mutation `changeElementCountTo` now uses `ElementCount`

>From 8825ce76ba2eba4b0dae1f1755afdfe2ba0a01bc Mon Sep 17 00:00:00 2001
From: Tim Gymnich <tim at gymni.ch>
Date: Thu, 6 Feb 2025 13:16:43 +0100
Subject: [PATCH 1/2] changeElementCount

---
 .../llvm/CodeGen/GlobalISel/LegalizerInfo.h        |  2 +-
 llvm/lib/CodeGen/GlobalISel/LegalizeMutations.cpp  |  6 ++----
 .../CodeGen/GlobalISel/LegalizerInfoTest.cpp       | 14 ++++++++------
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
index fd72a3898562e..8412042a780e8 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
@@ -380,7 +380,7 @@ LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx,
 
 /// Keep the same scalar or element type as \p TypeIdx, but take the number of
 /// elements from \p Ty.
-LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx, LLT Ty);
+LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx, ElementCount EC);
 
 /// Change the scalar size or element size to have the same scalar size as type
 /// index \p FromIndex. Unlike changeElementTo, this discards pointer types and
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizeMutations.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizeMutations.cpp
index 25c1db91b05d8..ded4df4edc14c 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizeMutations.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizeMutations.cpp
@@ -55,12 +55,10 @@ LegalizeMutation LegalizeMutations::changeElementCountTo(unsigned TypeIdx,
 }
 
 LegalizeMutation LegalizeMutations::changeElementCountTo(unsigned TypeIdx,
-                                                         LLT NewEltTy) {
+                                                         ElementCount EC) {
   return [=](const LegalityQuery &Query) {
     const LLT OldTy = Query.Types[TypeIdx];
-    ElementCount NewEltCount = NewEltTy.isVector() ? NewEltTy.getElementCount()
-                                                   : ElementCount::getFixed(1);
-    return std::make_pair(TypeIdx, OldTy.changeElementCount(NewEltCount));
+    return std::make_pair(TypeIdx, OldTy.changeElementCount(EC));
   };
 }
 
diff --git a/llvm/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp b/llvm/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp
index 988e307909232..836c81b524672 100644
--- a/llvm/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/LegalizerInfoTest.cpp
@@ -420,12 +420,14 @@ TEST(LegalizerInfoTest, RuleSets) {
 
     // Raw type form
     LI.getActionDefinitionsBuilder(G_ADD)
-      .fewerElementsIf(typeIs(0, v4s32), changeElementCountTo(0, v2s32))
-      .fewerElementsIf(typeIs(0, v8s32), changeElementCountTo(0, s32))
-      .fewerElementsIf(typeIs(0, LLT::scalable_vector(4, 16)),
-                       changeElementCountTo(0, LLT::scalable_vector(2, 16)))
-      .fewerElementsIf(typeIs(0, LLT::scalable_vector(8, 16)),
-                       changeElementCountTo(0, s16));
+        .fewerElementsIf(typeIs(0, v4s32),
+                         changeElementCountTo(0, ElementCount::getFixed(2)))
+        .fewerElementsIf(typeIs(0, v8s32),
+                         changeElementCountTo(0, ElementCount::getFixed(1)))
+        .fewerElementsIf(typeIs(0, LLT::scalable_vector(4, s16)),
+                         changeElementCountTo(0, ElementCount::getScalable(2)))
+        .fewerElementsIf(typeIs(0, LLT::scalable_vector(8, s16)),
+                         changeElementCountTo(0, ElementCount::getFixed(1)));
 
     LegacyInfo.computeTables();
 

>From 113daa9d142745e4858fb7b03e2c22ae593343a8 Mon Sep 17 00:00:00 2001
From: Denis Gerasimov <dengzmm at gmail.com>
Date: Mon, 15 Sep 2025 14:57:01 +0300
Subject: [PATCH 2/2] style

---
 llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
index 8412042a780e8..7b6b5dbf0be05 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
@@ -380,7 +380,8 @@ LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx,
 
 /// Keep the same scalar or element type as \p TypeIdx, but take the number of
 /// elements from \p Ty.
-LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx, ElementCount EC);
+LLVM_ABI LegalizeMutation changeElementCountTo(unsigned TypeIdx,
+                                               ElementCount EC);
 
 /// Change the scalar size or element size to have the same scalar size as type
 /// index \p FromIndex. Unlike changeElementTo, this discards pointer types and