[clang] 940e035 - [clang] Also disable scalable vectorisation for vectorize(disable) (#227254)
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Tue Sep 29 04:52:54 PDT 2026
Author: Gaëtan Bossu
Date: 2026-09-29T12:52:48+01:00
New Revision: 940e03584de8bfbcd86fc25de9a738d067d3a342
URL: https://github.com/llvm/llvm-project/commit/940e03584de8bfbcd86fc25de9a738d067d3a342
DIFF: https://github.com/llvm/llvm-project/commit/940e03584de8bfbcd86fc25de9a738d067d3a342.diff
LOG: [clang] Also disable scalable vectorisation for vectorize(disable) (#227254)
This ensures that #pragma clang loop vectorize(disable) also disables
scalable vectorisation. Only setting the width to 1 could potentially
enable LoopVectorizer to vectorize with VF = vscale x 1. Especially with
the -scalable-vectorization=preferred option.
Added:
Modified:
clang/lib/CodeGen/CGLoopInfo.cpp
clang/test/CodeGenCXX/pragma-loop-predicate.cpp
clang/test/CodeGenCXX/pragma-loop-safety.cpp
clang/test/CodeGenCXX/pragma-loop.cpp
Removed:
################################################################################
diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
index c13c2f6c60089..14e13af69b011 100644
--- a/clang/lib/CodeGen/CGLoopInfo.cpp
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -651,9 +651,10 @@ void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
case LoopHintAttr::Disable:
switch (Option) {
case LoopHintAttr::Vectorize:
- // Disable vectorization by specifying a width of 1.
+ // Disable vectorization by specifying a width of 1 and disabling
+ // scalable vectorization explicitly.
setVectorizeWidth(1);
- setVectorizeScalable(LoopAttributes::Unspecified);
+ setVectorizeScalable(LoopAttributes::Disable);
break;
case LoopHintAttr::Interleave:
// Disable interleaving by speciyfing a count of 1.
diff --git a/clang/test/CodeGenCXX/pragma-loop-predicate.cpp b/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
index bfacddc207f26..fdb23329e6121 100644
--- a/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
+++ b/clang/test/CodeGenCXX/pragma-loop-predicate.cpp
@@ -37,8 +37,8 @@ void test3(int *List, int Length) {
List[i] = i * 2;
}
-// Check that disabling vectorization means a vectorization width of 1, and
-// also that vectorization_predicate isn't enabled.
+// Check that disabling vectorization sets a width of 1 and disables
+// scalable vectorization without enabling vectorization_predicate.
void test4(int *List, int Length) {
// CHECK-LABEL: @{{.*}}test4{{.*}}(
// CHECK: br label {{.*}}, !llvm.loop ![[LOOP4:.*]]
@@ -113,13 +113,13 @@ void test9(int *List, int Length) {
// CHECK-NEXT: ![[LOOP3]] = distinct !{![[LOOP3]], [[MP]], [[GEN6]], [[GEN3]]}
-// CHECK-NEXT: ![[LOOP4]] = distinct !{![[LOOP4]], [[MP]], [[GEN10:![0-9]+]]}
+// CHECK-NEXT: ![[LOOP4]] = distinct !{![[LOOP4]], [[MP]], [[GEN10:![0-9]+]], [[GEN11:![0-9]+]]}
// CHECK-NEXT: [[GEN10]] = !{!"llvm.loop.vectorize.width", i32 1}
+// CHECK-NEXT: [[GEN11]] = !{!"llvm.loop.vectorize.scalable.disable"}
-// CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], [[MP]], [[GEN6]], [[GEN10]]}
+// CHECK-NEXT: ![[LOOP5]] = distinct !{![[LOOP5]], [[MP]], [[GEN6]], [[GEN10]], [[GEN11]]}
-// CHECK-NEXT: ![[LOOP6]] = distinct !{![[LOOP6]], [[MP]], [[GEN8]], [[GEN10]], [[GEN11:![0-9]+]]}
-// CHECK-NEXT: [[GEN11]] = !{!"llvm.loop.vectorize.scalable.disable"}
+// CHECK-NEXT: ![[LOOP6]] = distinct !{![[LOOP6]], [[MP]], [[GEN8]], [[GEN10]], [[GEN11]]}
// CHECK-NEXT: ![[LOOP7]] = distinct !{![[LOOP7]], [[MP]], [[GEN8]], [[GEN12:![0-9]+]], [[GEN11]], [[GEN3]]}
// CHECK-NEXT: [[GEN12]] = !{!"llvm.loop.vectorize.width", i32 4}
diff --git a/clang/test/CodeGenCXX/pragma-loop-safety.cpp b/clang/test/CodeGenCXX/pragma-loop-safety.cpp
index e2a7a124890a6..2114eb1643190 100644
--- a/clang/test/CodeGenCXX/pragma-loop-safety.cpp
+++ b/clang/test/CodeGenCXX/pragma-loop-safety.cpp
@@ -53,6 +53,7 @@ void interleave_test(int *List, int Length) {
// CHECK: ![[INTERLEAVE_1]] = !{!"llvm.loop.interleave.count", i32 1}
// CHECK: ![[INTENABLE_1]] = !{!"llvm.loop.vectorize.enable"}
// CHECK: ![[ACCESS_GROUP_8]] = distinct !{}
-// CHECK: ![[LOOP2_HINTS]] = distinct !{![[LOOP2_HINTS]], [[MP]], ![[PARALLEL_ACCESSES_11:[0-9]+]], ![[UNROLL_DISABLE]], ![[WIDTH_1:[0-9]+]], ![[INTENABLE_1]]}
+// CHECK: ![[LOOP2_HINTS]] = distinct !{![[LOOP2_HINTS]], [[MP]], ![[PARALLEL_ACCESSES_11:[0-9]+]], ![[UNROLL_DISABLE]], ![[WIDTH_1:[0-9]+]], ![[FIXED_VEC:[0-9]+]], ![[INTENABLE_1]]}
// CHECK: ![[PARALLEL_ACCESSES_11]] = !{!"llvm.loop.parallel_accesses", ![[ACCESS_GROUP_8]]}
// CHECK: ![[WIDTH_1]] = !{!"llvm.loop.vectorize.width", i32 1}
+// CHECK: ![[FIXED_VEC]] = !{!"llvm.loop.vectorize.scalable.disable"}
diff --git a/clang/test/CodeGenCXX/pragma-loop.cpp b/clang/test/CodeGenCXX/pragma-loop.cpp
index 75961aa86dcad..dbec1e3a1f5b1 100644
--- a/clang/test/CodeGenCXX/pragma-loop.cpp
+++ b/clang/test/CodeGenCXX/pragma-loop.cpp
@@ -278,7 +278,7 @@ void for_test_interleave_vectorize_disable_unroll(int *List, int Length) {
// CHECK-DAG: ![[LOOP_4]] = distinct !{![[LOOP_4]], ![[WIDTH_2]], ![[FIXED_VEC]], ![[INTERLEAVE_2]], ![[VECTORIZE_ENABLE]]}
-// CHECK-DAG: ![[LOOP_5]] = distinct !{![[LOOP_5]], ![[MP]], ![[UNROLL_DISABLE]], ![[DISTRIBUTE_DISABLE]], ![[WIDTH_1]]}
+// CHECK-DAG: ![[LOOP_5]] = distinct !{![[LOOP_5]], ![[MP]], ![[UNROLL_DISABLE]], ![[DISTRIBUTE_DISABLE]], ![[WIDTH_1]], ![[FIXED_VEC]]}
// CHECK-DAG: ![[LOOP_6]] = distinct !{![[LOOP_6]], ![[MP]], ![[WIDTH_2]], ![[FIXED_VEC]], ![[INTERLEAVE_2]], ![[VECTORIZE_ENABLE]], ![[FOLLOWUP_VECTOR_3]]}
@@ -309,5 +309,5 @@ void for_test_interleave_vectorize_disable_unroll(int *List, int Length) {
// CHECK-DAG: ![[LOOP_19]] = distinct !{![[LOOP_19]], ![[MP]], ![[UNROLL_DISABLE]], ![[DISTRIBUTE_DISABLE]], ![[WIDTH_1]], ![[SCALABLE_VEC]], ![[INTERLEAVE_4]], ![[VECTORIZE_ENABLE]]}
// CHECK-DAG: ![[LOOP_20]] = distinct !{![[LOOP_20]], ![[MP]], ![[UNROLL_DISABLE]], ![[DISTRIBUTE_DISABLE]], ![[WIDTH_1]], ![[FIXED_VEC]], ![[INTERLEAVE_4]]}
// CHECK-DAG: ![[LOOP_21]] = distinct !{![[LOOP_21]], ![[MP]], ![[UNROLL_DISABLE]], ![[DISTRIBUTE_DISABLE]], ![[WIDTH_1]], ![[FIXED_VEC]], ![[INTERLEAVE_4]]}
-// CHECK-DAG: ![[LOOP_22]] = distinct !{![[LOOP_22]], ![[MP]], ![[WIDTH_1]], ![[ISVECTORIZED]], ![[UNROLL_8]]}
-// CHECK-DAG: ![[LOOP_23]] = distinct !{![[LOOP_23]], ![[MP]], ![[WIDTH_1]], ![[INTERLEAVE_4]], ![[ISVECTORIZED]], ![[UNROLL_8]]}
+// CHECK-DAG: ![[LOOP_22]] = distinct !{![[LOOP_22]], ![[MP]], ![[WIDTH_1]], ![[FIXED_VEC]], ![[ISVECTORIZED]], ![[UNROLL_8]]}
+// CHECK-DAG: ![[LOOP_23]] = distinct !{![[LOOP_23]], ![[MP]], ![[WIDTH_1]], ![[FIXED_VEC]], ![[INTERLEAVE_4]], ![[ISVECTORIZED]], ![[UNROLL_8]]}
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