[llvm] 22637a8 - [Loads] Respect UseDerefAtPointSemantics in isDerefAndAlignedPointer. (#123196)

via llvm-commits llvm-commits at lists.llvm.org
Fri Jan 17 04:52:28 PST 2025


Author: Florian Hahn
Date: 2025-01-17T12:52:24Z
New Revision: 22637a877ae7fbfd5cf030400979fd4527eaebcf

URL: https://github.com/llvm/llvm-project/commit/22637a877ae7fbfd5cf030400979fd4527eaebcf
DIFF: https://github.com/llvm/llvm-project/commit/22637a877ae7fbfd5cf030400979fd4527eaebcf.diff

LOG: [Loads] Respect UseDerefAtPointSemantics in isDerefAndAlignedPointer. (#123196)

If a pointer gets freed, it may not be dereferenceable any longer, even
though there is a dominating dereferenceable assumption. As first step,
only consider assumptions if the pointer value cannot be freed if
UseDerefAtPointSemantics is used.

PR: https://github.com/llvm/llvm-project/pull/123196

Added: 
    

Modified: 
    llvm/lib/Analysis/Loads.cpp
    llvm/lib/IR/Value.cpp
    llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/Loads.cpp b/llvm/lib/Analysis/Loads.cpp
index 7bbd469bd035d3..11ccfa33821cad 100644
--- a/llvm/lib/Analysis/Loads.cpp
+++ b/llvm/lib/Analysis/Loads.cpp
@@ -25,6 +25,8 @@
 
 using namespace llvm;
 
+extern cl::opt<bool> UseDerefAtPointSemantics;
+
 static bool isAligned(const Value *Base, Align Alignment,
                       const DataLayout &DL) {
   return Base->getPointerAlignment(DL) >= Alignment;
@@ -168,7 +170,7 @@ static bool isDereferenceableAndAlignedPointer(
                                               Size, DL, CtxI, AC, DT, TLI,
                                               Visited, MaxDepth);
 
-  if (CtxI) {
+  if (CtxI && (!UseDerefAtPointSemantics || !V->canBeFreed())) {
     /// Look through assumes to see if both dereferencability and alignment can
     /// be proven by an assume if needed.
     RetainedKnowledge AlignRK;

diff  --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 65b63955b6f6d5..eddb67282fca46 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -36,7 +36,7 @@
 
 using namespace llvm;
 
-static cl::opt<bool> UseDerefAtPointSemantics(
+cl::opt<bool> UseDerefAtPointSemantics(
     "use-dereferenceable-at-point-semantics", cl::Hidden, cl::init(false),
     cl::desc("Deref attributes and metadata infer facts at definition only"));
 

diff  --git a/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll b/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
index 572511a5ffb926..90671689f1dce0 100644
--- a/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
+++ b/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
@@ -1,9 +1,9 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
-; RUN: opt -p loop-vectorize -force-vector-width=2 -use-dereferenceable-at-point-semantics=1 -S %s | FileCheck %s
+; RUN: opt -p loop-vectorize -force-vector-width=2 -use-dereferenceable-at-point-semantics -S %s | FileCheck %s
 
 declare void @llvm.assume(i1)
 
-define void @deref_assumption_in_header_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_header_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_header_constant_trip_count(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1:[0-9]+]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -104,7 +104,7 @@ exit:
   ret void
 }
 
-define void @align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -181,7 +181,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_too_small_in_header_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_too_small_in_header_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_too_small_in_header_constant_trip_count(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -282,7 +282,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_header_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_header_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_header_constant_trip_count_align_1(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -383,7 +383,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_header_constant_trip_count_align_via_arg_attribute(ptr noalias align 4 %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_header_constant_trip_count_align_via_arg_attribute(ptr noalias align 4 %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_header_constant_trip_count_align_via_arg_attribute(
 ; CHECK-SAME: ptr noalias align 4 [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -484,7 +484,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_header_constant_trip_count_align_not_known(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_header_constant_trip_count_align_not_known(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_header_constant_trip_count_align_not_known(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -585,7 +585,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_then_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_then_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_then_constant_trip_count(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -682,7 +682,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_latch_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_latch_constant_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_latch_constant_trip_count(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -785,7 +785,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_header_variable_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c, i64 %N) nofree {
+define void @deref_assumption_in_header_variable_trip_count(ptr noalias %a, ptr noalias %b, ptr noalias %c, i64 %N) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_header_variable_trip_count(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]], i64 [[N:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -890,7 +890,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_preheader_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_preheader_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_preheader_constant_trip_count_align_1(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -968,7 +968,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_1(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_1(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -1063,7 +1063,7 @@ exit:
   ret void
 }
 
-define void @align_and_deref_assumption_in_preheader_constant_trip_count_align_4(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @align_and_deref_assumption_in_preheader_constant_trip_count_align_4(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @align_and_deref_assumption_in_preheader_constant_trip_count_align_4(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -1142,7 +1142,7 @@ exit:
 }
 
 
-define void @deref_assumption_in_preheader_constant_trip_count_align_4_known_via_argument_attr(ptr noalias align 4 %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_preheader_constant_trip_count_align_4_known_via_argument_attr(ptr noalias align 4 %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_preheader_constant_trip_count_align_4_known_via_argument_attr(
 ; CHECK-SAME: ptr noalias align 4 [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -1220,7 +1220,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_in_preheader_constant_trip_count_align_4_not_known(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_in_preheader_constant_trip_count_align_4_not_known(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_in_preheader_constant_trip_count_align_4_not_known(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -1315,7 +1315,7 @@ exit:
   ret void
 }
 
-define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_4(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree {
+define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_4(ptr noalias %a, ptr noalias %b, ptr noalias %c) nofree nosync{
 ; CHECK-LABEL: define void @deref_assumption_too_small_in_preheader_constant_trip_count_align_4(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
@@ -1410,8 +1410,8 @@ exit:
   ret void
 }
 
-; %a may be freeed between the dereferenceable assumption and accesses.
-; FIXME: It is not safe to use with -use-dereferenceable-at-point-semantics.
+; %a may be freed between the dereferenceable assumption and accesses.
+; It is not safe to use with -use-dereferenceable-at-point-semantics.
 define void @may_free_align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(ptr noalias %a, ptr noalias %b, ptr noalias %c) {
 ; CHECK-LABEL: define void @may_free_align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(
 ; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) {
@@ -1422,16 +1422,29 @@ define void @may_free_align_deref_assumption_in_header_constant_trip_count_loop_
 ; CHECK:       [[VECTOR_PH]]:
 ; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; CHECK:       [[VECTOR_BODY]]:
-; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
 ; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 0
 ; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
 ; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
 ; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
-; CHECK-NEXT:    [[TMP5:%.*]] = load i32, ptr [[A]], align 4
+; CHECK-NEXT:    [[TMP4:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = extractelement <2 x i1> [[TMP4]], i32 0
+; CHECK-NEXT:    br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
+; CHECK:       [[PRED_LOAD_IF]]:
 ; CHECK-NEXT:    [[TMP15:%.*]] = load i32, ptr [[A]], align 4
-; CHECK-NEXT:    [[TMP13:%.*]] = insertelement <2 x i32> poison, i32 [[TMP5]], i32 0
-; CHECK-NEXT:    [[TMP11:%.*]] = insertelement <2 x i32> [[TMP13]], i32 [[TMP15]], i32 1
+; CHECK-NEXT:    [[TMP7:%.*]] = insertelement <2 x i32> poison, i32 [[TMP15]], i32 0
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE]]
+; CHECK:       [[PRED_LOAD_CONTINUE]]:
+; CHECK-NEXT:    [[TMP12:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP7]], %[[PRED_LOAD_IF]] ]
+; CHECK-NEXT:    [[TMP13:%.*]] = extractelement <2 x i1> [[TMP4]], i32 1
+; CHECK-NEXT:    br i1 [[TMP13]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
+; CHECK:       [[PRED_LOAD_IF1]]:
+; CHECK-NEXT:    [[TMP14:%.*]] = load i32, ptr [[A]], align 4
+; CHECK-NEXT:    [[TMP16:%.*]] = insertelement <2 x i32> [[TMP12]], i32 [[TMP14]], i32 1
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE2]]
+; CHECK:       [[PRED_LOAD_CONTINUE2]]:
+; CHECK-NEXT:    [[TMP11:%.*]] = phi <2 x i32> [ [[TMP12]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP16]], %[[PRED_LOAD_IF1]] ]
 ; CHECK-NEXT:    [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[TMP11]]
 ; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
 ; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i32, ptr [[TMP8]], i32 0
@@ -1491,6 +1504,103 @@ exit:
   ret void
 }
 
+; %a may be freed between the dereferenceable assumption and accesses.
+; It is not safe to use with -use-dereferenceable-at-point-semantics.
+define void @may_free_local_ptr_align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(ptr noalias %b, ptr noalias %c) nofree nosync {
+; CHECK-LABEL: define void @may_free_local_ptr_align_deref_assumption_in_header_constant_trip_count_loop_invariant_ptr(
+; CHECK-SAME: ptr noalias [[B:%.*]], ptr noalias [[C:%.*]]) #[[ATTR1]] {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[A:%.*]] = call ptr @get_ptr()
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr [[A]], i64 4), "dereferenceable"(ptr [[A]], i64 4) ]
+; CHECK-NEXT:    call void @may_free()
+; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 0
+; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
+; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT:    [[TMP4:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
+; CHECK-NEXT:    [[TMP5:%.*]] = extractelement <2 x i1> [[TMP4]], i32 0
+; CHECK-NEXT:    br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
+; CHECK:       [[PRED_LOAD_IF]]:
+; CHECK-NEXT:    [[TMP6:%.*]] = load i32, ptr [[A]], align 4
+; CHECK-NEXT:    [[TMP7:%.*]] = insertelement <2 x i32> poison, i32 [[TMP6]], i32 0
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE]]
+; CHECK:       [[PRED_LOAD_CONTINUE]]:
+; CHECK-NEXT:    [[TMP8:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP7]], %[[PRED_LOAD_IF]] ]
+; CHECK-NEXT:    [[TMP9:%.*]] = extractelement <2 x i1> [[TMP4]], i32 1
+; CHECK-NEXT:    br i1 [[TMP9]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
+; CHECK:       [[PRED_LOAD_IF1]]:
+; CHECK-NEXT:    [[TMP10:%.*]] = load i32, ptr [[A]], align 4
+; CHECK-NEXT:    [[TMP11:%.*]] = insertelement <2 x i32> [[TMP8]], i32 [[TMP10]], i32 1
+; CHECK-NEXT:    br label %[[PRED_LOAD_CONTINUE2]]
+; CHECK:       [[PRED_LOAD_CONTINUE2]]:
+; CHECK-NEXT:    [[TMP12:%.*]] = phi <2 x i32> [ [[TMP8]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP11]], %[[PRED_LOAD_IF1]] ]
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[TMP12]]
+; CHECK-NEXT:    [[TMP13:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
+; CHECK-NEXT:    [[TMP14:%.*]] = getelementptr inbounds i32, ptr [[TMP13]], i32 0
+; CHECK-NEXT:    store <2 x i32> [[PREDPHI]], ptr [[TMP14]], align 4
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1000
+; CHECK-NEXT:    br i1 [[TMP15]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP34:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br i1 true, label %[[EXIT:.*]], label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 1000, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    br label %[[LOOP_HEADER:.*]]
+; CHECK:       [[LOOP_HEADER]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
+; CHECK-NEXT:    [[GEP_B:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[IV]]
+; CHECK-NEXT:    [[L_B:%.*]] = load i32, ptr [[GEP_B]], align 4
+; CHECK-NEXT:    [[C_1:%.*]] = icmp sge i32 [[L_B]], 0
+; CHECK-NEXT:    br i1 [[C_1]], label %[[LOOP_LATCH]], label %[[LOOP_THEN:.*]]
+; CHECK:       [[LOOP_THEN]]:
+; CHECK-NEXT:    [[L_A:%.*]] = load i32, ptr [[A]], align 4
+; CHECK-NEXT:    br label %[[LOOP_LATCH]]
+; CHECK:       [[LOOP_LATCH]]:
+; CHECK-NEXT:    [[MERGE:%.*]] = phi i32 [ [[L_A]], %[[LOOP_THEN]] ], [ [[L_B]], %[[LOOP_HEADER]] ]
+; CHECK-NEXT:    [[GEP_C:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[IV]]
+; CHECK-NEXT:    store i32 [[MERGE]], ptr [[GEP_C]], align 4
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV_NEXT]], 1000
+; CHECK-NEXT:    br i1 [[EC]], label %[[EXIT]], label %[[LOOP_HEADER]], !llvm.loop [[LOOP35:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a = call ptr @get_ptr()
+  call void @llvm.assume(i1 true) [ "align"(ptr %a, i64 4), "dereferenceable"(ptr %a, i64 4) ]
+  call void @may_free()
+  br label %loop.header
+
+loop.header:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep.b = getelementptr inbounds i32, ptr %b, i64 %iv
+  %l.b = load i32, ptr %gep.b, align 4
+  %c.1 = icmp sge i32 %l.b, 0
+  br i1 %c.1, label %loop.latch, label %loop.then
+
+loop.then:
+  %l.a = load i32, ptr %a, align 4
+  br label %loop.latch
+
+loop.latch:
+  %merge = phi i32 [ %l.a, %loop.then ], [ %l.b, %loop.header ]
+  %gep.c = getelementptr inbounds i32, ptr %c, i64 %iv
+  store i32 %merge, ptr %gep.c, align 4
+  %iv.next = add nuw nsw i64 %iv, 1
+  %ec = icmp eq i64 %iv.next, 1000
+  br i1 %ec, label %exit, label %loop.header
+
+exit:
+  ret void
+}
+
+declare ptr @get_ptr()
 declare void @may_free()
 
 ;.
@@ -1528,4 +1638,6 @@ declare void @may_free()
 ; CHECK: [[LOOP31]] = distinct !{[[LOOP31]], [[META2]], [[META1]]}
 ; CHECK: [[LOOP32]] = distinct !{[[LOOP32]], [[META1]], [[META2]]}
 ; CHECK: [[LOOP33]] = distinct !{[[LOOP33]], [[META2]], [[META1]]}
+; CHECK: [[LOOP34]] = distinct !{[[LOOP34]], [[META1]], [[META2]]}
+; CHECK: [[LOOP35]] = distinct !{[[LOOP35]], [[META2]], [[META1]]}
 ;.


        


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