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release/21.x: [llvm][sroa] Disable support for invariant.group (#151743) #152099

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@llvmbot llvmbot commented Aug 5, 2025

Backport 155359c

Requested by: @nikic

Resolves llvm#151574.

> SROA pass does not perform aggregate load/store rewriting on a pointer
whose source is a `launder.invariant.group`.
>
> This causes failed assertion in `AllocaSlices`.
>
> ```
> void (anonymous
namespace)::AllocaSlices::SliceBuilder::visitStoreInst(StoreInst &):
> Assertion `(!SI.isSimple() || ValOp->getType()->isSingleValueType())
&&
>  "All simple FCA stores should have been pre-split"' failed.
> ```

Disables support for `{launder,strip}.invariant.group` intrinsics in
SROA.

Updates SROA test for `invariant.group` support.

(cherry picked from commit 155359c)
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llvmbot commented Aug 5, 2025

@nikic What do you think about merging this PR to the release branch?

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llvmbot commented Aug 5, 2025

@llvm/pr-subscribers-llvm-transforms

Author: None (llvmbot)

Changes

Backport 155359c

Requested by: @nikic


Full diff: https://github.com/llvm/llvm-project/pull/152099.diff

2 Files Affected:

  • (modified) llvm/lib/Transforms/Scalar/SROA.cpp (+2-13)
  • (modified) llvm/test/Transforms/SROA/invariant-group.ll (+82-7)
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 70b4552190a4e..f537b0d3fbd75 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1258,8 +1258,7 @@ class AllocaSlices::SliceBuilder : public PtrUseVisitor<SliceBuilder> {
            "Map index doesn't point back to a slice with this user.");
   }
 
-  // Disable SRoA for any intrinsics except for lifetime invariants and
-  // invariant group.
+  // Disable SRoA for any intrinsics except for lifetime invariants.
   // FIXME: What about debug intrinsics? This matches old behavior, but
   // doesn't make sense.
   void visitIntrinsicInst(IntrinsicInst &II) {
@@ -1279,12 +1278,6 @@ class AllocaSlices::SliceBuilder : public PtrUseVisitor<SliceBuilder> {
       return;
     }
 
-    if (II.isLaunderOrStripInvariantGroup()) {
-      insertUse(II, Offset, AllocSize, true);
-      enqueueUsers(II);
-      return;
-    }
-
     Base::visitIntrinsicInst(II);
   }
 
@@ -3618,8 +3611,7 @@ class AllocaSliceRewriter : public InstVisitor<AllocaSliceRewriter, bool> {
   }
 
   bool visitIntrinsicInst(IntrinsicInst &II) {
-    assert((II.isLifetimeStartOrEnd() || II.isLaunderOrStripInvariantGroup() ||
-            II.isDroppable()) &&
+    assert((II.isLifetimeStartOrEnd() || II.isDroppable()) &&
            "Unexpected intrinsic!");
     LLVM_DEBUG(dbgs() << "    original: " << II << "\n");
 
@@ -3633,9 +3625,6 @@ class AllocaSliceRewriter : public InstVisitor<AllocaSliceRewriter, bool> {
       return true;
     }
 
-    if (II.isLaunderOrStripInvariantGroup())
-      return true;
-
     assert(II.getArgOperand(1) == OldPtr);
     // Lifetime intrinsics are only promotable if they cover the whole alloca.
     // Therefore, we drop lifetime intrinsics which don't cover the whole
diff --git a/llvm/test/Transforms/SROA/invariant-group.ll b/llvm/test/Transforms/SROA/invariant-group.ll
index 1be6f6e2fc32b..c9c9e031ca95f 100644
--- a/llvm/test/Transforms/SROA/invariant-group.ll
+++ b/llvm/test/Transforms/SROA/invariant-group.ll
@@ -11,10 +11,17 @@ declare i32 @somevalue()
 
 define void @f() {
 ; CHECK-LABEL: @f(
+; CHECK-NEXT:    [[A:%.*]] = alloca [[T:%.*]], align 8
+; CHECK-NEXT:    [[A1_I8_INV:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[A]])
+; CHECK-NEXT:    [[A2:%.*]] = getelementptr inbounds [[T]], ptr [[A]], i32 0, i32 1
 ; CHECK-NEXT:    [[SV1:%.*]] = call i32 @somevalue()
 ; CHECK-NEXT:    [[SV2:%.*]] = call i32 @somevalue()
-; CHECK-NEXT:    call void @h(i32 [[SV1]])
-; CHECK-NEXT:    call void @h(i32 [[SV2]])
+; CHECK-NEXT:    store i32 [[SV1]], ptr [[A1_I8_INV]], align 4, !invariant.group [[META0:![0-9]+]]
+; CHECK-NEXT:    store i32 [[SV2]], ptr [[A2]], align 4
+; CHECK-NEXT:    [[V1:%.*]] = load i32, ptr [[A1_I8_INV]], align 4, !invariant.group [[META0]]
+; CHECK-NEXT:    [[V2:%.*]] = load i32, ptr [[A2]], align 4
+; CHECK-NEXT:    call void @h(i32 [[V1]])
+; CHECK-NEXT:    call void @h(i32 [[V2]])
 ; CHECK-NEXT:    ret void
 ;
   %a = alloca %t
@@ -44,7 +51,7 @@ define void @g() {
 ; CHECK-NEXT:    [[A2:%.*]] = getelementptr inbounds [[T]], ptr [[A]], i32 0, i32 1
 ; CHECK-NEXT:    [[SV1:%.*]] = call i32 @somevalue()
 ; CHECK-NEXT:    [[SV2:%.*]] = call i32 @somevalue()
-; CHECK-NEXT:    store i32 [[SV1]], ptr [[A1_I8_INV]], align 4, !invariant.group [[META0:![0-9]+]]
+; CHECK-NEXT:    store i32 [[SV1]], ptr [[A1_I8_INV]], align 4, !invariant.group [[META0]]
 ; CHECK-NEXT:    store i32 [[SV2]], ptr [[A2]], align 4
 ; CHECK-NEXT:    [[V1:%.*]] = load i32, ptr [[A1_I8_INV]], align 4, !invariant.group [[META0]]
 ; CHECK-NEXT:    [[V2:%.*]] = load i32, ptr [[A2]], align 4
@@ -81,6 +88,9 @@ define void @g() {
 
 define void @store_and_launder() {
 ; CHECK-LABEL: @store_and_launder(
+; CHECK-NEXT:    [[VALPTR:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    store i32 0, ptr [[VALPTR]], align 4
+; CHECK-NEXT:    [[BARR:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[VALPTR]])
 ; CHECK-NEXT:    ret void
 ;
   %valptr = alloca i32, align 4
@@ -91,7 +101,10 @@ define void @store_and_launder() {
 
 define i32 @launder_and_load() {
 ; CHECK-LABEL: @launder_and_load(
-; CHECK-NEXT:    ret i32 undef
+; CHECK-NEXT:    [[VALPTR:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[BARR:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[VALPTR]])
+; CHECK-NEXT:    [[V2:%.*]] = load i32, ptr [[VALPTR]], align 4
+; CHECK-NEXT:    ret i32 [[V2]]
 ;
   %valptr = alloca i32, align 4
   %barr = call ptr @llvm.launder.invariant.group.p0(ptr %valptr)
@@ -101,6 +114,9 @@ define i32 @launder_and_load() {
 
 define void @launder_and_ptr_arith() {
 ; CHECK-LABEL: @launder_and_ptr_arith(
+; CHECK-NEXT:    [[VALPTR:%.*]] = alloca i32, align 4
+; CHECK-NEXT:    [[BARR:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[VALPTR]])
+; CHECK-NEXT:    [[A2:%.*]] = getelementptr inbounds i32, ptr [[VALPTR]], i32 0
 ; CHECK-NEXT:    ret void
 ;
   %valptr = alloca i32, align 4
@@ -140,9 +156,13 @@ end:
 
 define void @partial_promotion_of_alloca() {
 ; CHECK-LABEL: @partial_promotion_of_alloca(
-; CHECK-NEXT:    [[STRUCT_PTR_SROA_2:%.*]] = alloca i32, align 4
-; CHECK-NEXT:    store volatile i32 0, ptr [[STRUCT_PTR_SROA_2]], align 4
-; CHECK-NEXT:    [[STRUCT_PTR_SROA_2_0_STRUCT_PTR_SROA_2_4_LOAD_VAL:%.*]] = load volatile i32, ptr [[STRUCT_PTR_SROA_2]], align 4
+; CHECK-NEXT:    [[STRUCT_PTR:%.*]] = alloca [[T:%.*]], align 4
+; CHECK-NEXT:    [[FIELD_PTR:%.*]] = getelementptr inbounds [[T]], ptr [[STRUCT_PTR]], i32 0, i32 0
+; CHECK-NEXT:    store i32 0, ptr [[FIELD_PTR]], align 4
+; CHECK-NEXT:    [[VOLATILE_FIELD_PTR:%.*]] = getelementptr inbounds [[T]], ptr [[STRUCT_PTR]], i32 0, i32 1
+; CHECK-NEXT:    store volatile i32 0, ptr [[VOLATILE_FIELD_PTR]], align 4, !invariant.group [[META0]]
+; CHECK-NEXT:    [[BARR:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[STRUCT_PTR]])
+; CHECK-NEXT:    [[LOAD_VAL:%.*]] = load volatile i32, ptr [[VOLATILE_FIELD_PTR]], align 4, !invariant.group [[META0]]
 ; CHECK-NEXT:    ret void
 ;
   %struct_ptr = alloca %t, align 4
@@ -155,6 +175,61 @@ define void @partial_promotion_of_alloca() {
   ret void
 }
 
+define void @memcpy_after_laundering_alloca(ptr %ptr) {
+; CHECK-LABEL: @memcpy_after_laundering_alloca(
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca { i64, i64 }, align 8
+; CHECK-NEXT:    [[LAUNDER:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[ALLOCA]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr [[LAUNDER]], ptr [[PTR:%.*]], i64 16, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %alloca = alloca { i64, i64 }, align 8
+  %launder = call ptr @llvm.launder.invariant.group.p0(ptr %alloca)
+  call void @llvm.memcpy.p0.p0.i64(ptr %launder, ptr %ptr, i64 16, i1 false)
+  ret void
+}
+
+define void @memcpy_after_laundering_alloca_slices(ptr %ptr) {
+; CHECK-LABEL: @memcpy_after_laundering_alloca_slices(
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca { [16 x i8], i64, [16 x i8] }, align 8
+; CHECK-NEXT:    [[LAUNDER:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[ALLOCA]])
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[LAUNDER]], i64 16
+; CHECK-NEXT:    store i64 0, ptr [[GEP]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr [[LAUNDER]], ptr [[PTR:%.*]], i64 40, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %alloca = alloca { [16 x i8], i64, [16 x i8] }, align 8
+  %launder = call ptr @llvm.launder.invariant.group.p0(ptr %alloca)
+  %gep = getelementptr i8, ptr %launder, i64 16
+  store i64 0, ptr %gep
+  call void @llvm.memcpy.p0.p0.i64(ptr %launder, ptr %ptr, i64 40, i1 false)
+  ret void
+}
+
+define void @test_agg_store() {
+; CHECK-LABEL: @test_agg_store(
+; CHECK-NEXT:    [[STRUCT_PTR:%.*]] = alloca [[T:%.*]], i64 1, align 4
+; CHECK-NEXT:    [[STRUCT_PTR_FRESH:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[STRUCT_PTR]])
+; CHECK-NEXT:    [[STRUCT:%.*]] = call [[T]] @[[MAKE_T:[a-zA-Z0-9_$\"\\.-]*[a-zA-Z_$\"\\.-][a-zA-Z0-9_$\"\\.-]*]]()
+; CHECK-NEXT:    store [[T]] [[STRUCT]], ptr [[STRUCT_PTR_FRESH]], align 4, !invariant.group [[META0]]
+; CHECK-NEXT:    [[FIRST_PTR:%.*]] = getelementptr [[T]], ptr [[STRUCT_PTR_FRESH]], i32 0, i32 0
+; CHECK-NEXT:    [[FIRST:%.*]] = load i32, ptr [[FIRST_PTR]], align 4
+; CHECK-NEXT:    [[SECOND_PTR:%.*]] = getelementptr [[T]], ptr [[STRUCT_PTR_FRESH]], i32 0, i32 1
+; CHECK-NEXT:    [[SECOND:%.*]] = load i32, ptr [[SECOND_PTR]], align 4
+; CHECK-NEXT:    ret void
+;
+  %struct_ptr = alloca %t, i64 1, align 4
+  %struct_ptr_fresh = call ptr @llvm.launder.invariant.group.p0(ptr %struct_ptr)
+  %struct = call %t @make_t()
+  store %t %struct, ptr %struct_ptr_fresh, align 4, !invariant.group !0
+  %first_ptr = getelementptr %t, ptr %struct_ptr_fresh, i32 0, i32 0
+  %first = load i32, ptr %first_ptr, align 4
+  %second_ptr = getelementptr %t, ptr %struct_ptr_fresh, i32 0, i32 1
+  %second = load i32, ptr %second_ptr, align 4
+  ret void
+}
+
+declare %t @make_t()
+
 declare void @use(ptr)
 
 !0 = !{}

@tru tru moved this from Needs Triage to Needs Review in LLVM Release Status Aug 5, 2025
@github-project-automation github-project-automation bot moved this from Needs Review to Needs Merge in LLVM Release Status Aug 5, 2025
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