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author | Shilei Tian <i@tianshilei.me> | 2022-08-06 16:50:30 -0400 |
---|---|---|
committer | Tobias Hieta <tobias@hieta.se> | 2022-08-15 09:31:02 +0200 |
commit | a9ac5ac72816978bcf1a9d11def8e57dee25d330 (patch) | |
tree | f88ab5b4575ba2201afe3c7e4e144e5288b57e30 /clang/test | |
parent | 5932bf1730629a1c2673cfdd31d5d823e62a33c3 (diff) | |
download | llvm-a9ac5ac72816978bcf1a9d11def8e57dee25d330.zip llvm-a9ac5ac72816978bcf1a9d11def8e57dee25d330.tar.gz llvm-a9ac5ac72816978bcf1a9d11def8e57dee25d330.tar.bz2 |
[Clang][OpenMP] Fix the issue that `llvm.lifetime.end` is emitted too early for variables captured in linear clause
Currently if an OpenMP program uses `linear` clause, and is compiled with
optimization, `llvm.lifetime.end` for variables listed in `linear` clause are
emitted too early such that there could still be uses after that. Let's take the
following code as example:
```
// loop.c
int j;
int *u;
void loop(int n) {
int i;
for (i = 0; i < n; ++i) {
++j;
u = &j;
}
}
```
We compile using the command:
```
clang -cc1 -fopenmp-simd -O3 -x c -triple x86_64-apple-darwin10 -emit-llvm loop.c -o loop.ll
```
The following IR (simplified) will be generated:
```
@j = local_unnamed_addr global i32 0, align 4
@u = local_unnamed_addr global ptr null, align 8
define void @loop(i32 noundef %n) local_unnamed_addr {
entry:
%j = alloca i32, align 4
%cmp = icmp sgt i32 %n, 0
br i1 %cmp, label %simd.if.then, label %simd.if.end
simd.if.then: ; preds = %entry
call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %j)
store ptr %j, ptr @u, align 8
call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %j)
%0 = load i32, ptr %j, align 4
store i32 %0, ptr @j, align 4
br label %simd.if.end
simd.if.end: ; preds = %simd.if.then, %entry
ret void
}
```
The most important part is:
```
call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %j)
%0 = load i32, ptr %j, align 4
store i32 %0, ptr @j, align 4
```
`%j` is still loaded after `@llvm.lifetime.end.p0(i64 4, ptr nonnull %j)`. This
could cause the backend incorrectly optimizes the code and further generates
incorrect code. The root cause is, when we emit a construct that could have
`linear` clause, it usually has the following pattern:
```
EmitOMPLinearClauseInit(S)
{
OMPPrivateScope LoopScope(*this);
...
EmitOMPLinearClause(S, LoopScope);
...
(void)LoopScope.Privatize();
...
}
EmitOMPLinearClauseFinal(S, [](CodeGenFunction &) { return nullptr; });
```
Variables that need to be privatized are added into `LoopScope`, which also
serves as a RAII object. When `LoopScope` is destructed and if optimization is
enabled, a `@llvm.lifetime.end` is also emitted for each privatized variable.
However, the writing back to original variables in `linear` clause happens after
the scope in `EmitOMPLinearClauseFinal`, causing the issue we see above.
A quick "fix" seems to be, moving `EmitOMPLinearClauseFinal` inside the scope.
However, it doesn't work. That's because the local variable map has been updated
by `LoopScope` such that a variable declaration is mapped to the privatized
variable, instead of the actual one. In that way, the following code will be
generated:
```
%0 = load i32, ptr %j, align 4
store i32 %0, ptr %j, align 4
call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %j)
```
Well, now the life time is correct, but apparently the writing back is broken.
In this patch, a new function `OMPPrivateScope::restoreMap` is added and called
before calling `EmitOMPLinearClauseFinal`. This can make sure that
`EmitOMPLinearClauseFinal` can find the orignal varaibls to write back.
Fixes #56913.
Reviewed By: ABataev
Differential Revision: https://reviews.llvm.org/D131272
(cherry picked from commit e21202dac18ed7f718d26a0e131f96b399b4891c)
Diffstat (limited to 'clang/test')
-rw-r--r-- | clang/test/OpenMP/bug56913.c | 32 | ||||
-rw-r--r-- | clang/test/OpenMP/for_linear_codegen.cpp | 18 | ||||
-rw-r--r-- | clang/test/OpenMP/parallel_master_taskloop_simd_lastprivate_codegen.cpp | 8 |
3 files changed, 47 insertions, 11 deletions
diff --git a/clang/test/OpenMP/bug56913.c b/clang/test/OpenMP/bug56913.c new file mode 100644 index 0000000..cc72316 --- /dev/null +++ b/clang/test/OpenMP/bug56913.c @@ -0,0 +1,32 @@ +// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --function-signature --include-generated-funcs --prefix-filecheck-ir-name _ +// RUN: %clang_cc1 -fopenmp-simd -O1 -x c -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK + +int j; +int *u; + +void loop(int n) { + int i; +#pragma omp parallel master taskloop simd linear(j) + for (i = 0; i < n; ++i) { + ++j; + u = &j; + } +} +// CHECK-LABEL: define {{[^@]+}}@loop +// CHECK-SAME: (i32 noundef [[N:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] { +// CHECK-NEXT: entry: +// CHECK-NEXT: [[J:%.*]] = alloca i32, align 4 +// CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[N]], 0 +// CHECK-NEXT: br i1 [[CMP]], label [[SIMD_IF_THEN:%.*]], label [[SIMD_IF_END:%.*]] +// CHECK: simd.if.then: +// CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr @j, align 4, !tbaa [[TBAA2:![0-9]+]] +// CHECK-NEXT: call void @llvm.lifetime.start.p0(i64 4, ptr nonnull [[J]]) #[[ATTR2:[0-9]+]] +// CHECK-NEXT: store ptr [[J]], ptr @u, align 8, !tbaa [[TBAA6:![0-9]+]], !llvm.access.group [[ACC_GRP8:![0-9]+]] +// CHECK-NEXT: [[INC_LE:%.*]] = add i32 [[TMP0]], [[N]] +// CHECK-NEXT: store i32 [[INC_LE]], ptr [[J]], align 4, !tbaa [[TBAA2]] +// CHECK-NEXT: store i32 [[INC_LE]], ptr @j, align 4, !tbaa [[TBAA2]] +// CHECK-NEXT: call void @llvm.lifetime.end.p0(i64 4, ptr nonnull [[J]]) #[[ATTR2]] +// CHECK-NEXT: br label [[SIMD_IF_END]] +// CHECK: simd.if.end: +// CHECK-NEXT: ret void +// diff --git a/clang/test/OpenMP/for_linear_codegen.cpp b/clang/test/OpenMP/for_linear_codegen.cpp index 05ccf94..c7c9324 100644 --- a/clang/test/OpenMP/for_linear_codegen.cpp +++ b/clang/test/OpenMP/for_linear_codegen.cpp @@ -322,18 +322,18 @@ int main() { // CHECK1-NEXT: br label [[OMP_LOOP_EXIT:%.*]] // CHECK1: omp.loop.exit: // CHECK1-NEXT: call void @__kmpc_for_static_fini(%struct.ident_t* @[[GLOB2]], i32 [[TMP5]]) -// CHECK1-NEXT: [[TMP19:%.*]] = bitcast i64* [[DOTLVAR__ADDR]] to i8* -// CHECK1-NEXT: call void @__kmpc_free(i32 [[TMP5]], i8* [[TMP19]], i8* inttoptr (i64 5 to i8*)) -// CHECK1-NEXT: [[TMP20:%.*]] = load i32, i32* [[DOTOMP_IS_LAST]], align 4 -// CHECK1-NEXT: [[TMP21:%.*]] = icmp ne i32 [[TMP20]], 0 -// CHECK1-NEXT: br i1 [[TMP21]], label [[DOTOMP_LINEAR_PU:%.*]], label [[DOTOMP_LINEAR_PU_DONE:%.*]] +// CHECK1-NEXT: [[TMP19:%.*]] = load i32, i32* [[DOTOMP_IS_LAST]], align 4 +// CHECK1-NEXT: [[TMP20:%.*]] = icmp ne i32 [[TMP19]], 0 +// CHECK1-NEXT: br i1 [[TMP20]], label [[DOTOMP_LINEAR_PU:%.*]], label [[DOTOMP_LINEAR_PU_DONE:%.*]] // CHECK1: .omp.linear.pu: -// CHECK1-NEXT: [[TMP22:%.*]] = load float*, float** [[PVAR2]], align 8 -// CHECK1-NEXT: store float* [[TMP22]], float** [[TMP0]], align 8 -// CHECK1-NEXT: [[TMP23:%.*]] = load i64, i64* [[DOTLVAR__ADDR]], align 8 -// CHECK1-NEXT: store i64 [[TMP23]], i64* [[TMP1]], align 8 +// CHECK1-NEXT: [[TMP21:%.*]] = load float*, float** [[PVAR2]], align 8 +// CHECK1-NEXT: store float* [[TMP21]], float** [[TMP0]], align 8 +// CHECK1-NEXT: [[TMP22:%.*]] = load i64, i64* [[DOTLVAR__ADDR]], align 8 +// CHECK1-NEXT: store i64 [[TMP22]], i64* [[TMP1]], align 8 // CHECK1-NEXT: br label [[DOTOMP_LINEAR_PU_DONE]] // CHECK1: .omp.linear.pu.done: +// CHECK1-NEXT: [[TMP23:%.*]] = bitcast i64* [[DOTLVAR__ADDR]] to i8* +// CHECK1-NEXT: call void @__kmpc_free(i32 [[TMP5]], i8* [[TMP23]], i8* inttoptr (i64 5 to i8*)) // CHECK1-NEXT: call void @__kmpc_barrier(%struct.ident_t* @[[GLOB1]], i32 [[TMP5]]) // CHECK1-NEXT: ret void // diff --git a/clang/test/OpenMP/parallel_master_taskloop_simd_lastprivate_codegen.cpp b/clang/test/OpenMP/parallel_master_taskloop_simd_lastprivate_codegen.cpp index ef01591..ffda7d2a 100644 --- a/clang/test/OpenMP/parallel_master_taskloop_simd_lastprivate_codegen.cpp +++ b/clang/test/OpenMP/parallel_master_taskloop_simd_lastprivate_codegen.cpp @@ -1847,8 +1847,12 @@ void loop() { // CHECK6-NEXT: [[TMP38:%.*]] = icmp ne i32 [[TMP37]], 0 // CHECK6-NEXT: br i1 [[TMP38]], label [[DOTOMP_LINEAR_PU_I:%.*]], label [[DOTOMP_OUTLINED__1_EXIT:%.*]] // CHECK6: .omp.linear.pu.i: -// CHECK6-NEXT: [[TMP39:%.*]] = load i32, i32* [[J_I]], align 4, !noalias !14 -// CHECK6-NEXT: store i32 [[TMP39]], i32* [[J_I]], align 4, !noalias !14 +// CHECK6-NEXT: [[TMP39:%.*]] = getelementptr inbounds [[STRUCT_ANON]], %struct.anon* [[TMP20]], i32 0, i32 0 +// CHECK6-NEXT: [[TMP40:%.*]] = load i32*, i32** [[TMP39]], align 8 +// CHECK6-NEXT: [[TMP41:%.*]] = getelementptr inbounds [[STRUCT_ANON]], %struct.anon* [[TMP20]], i32 0, i32 1 +// CHECK6-NEXT: [[TMP42:%.*]] = load i32*, i32** [[TMP41]], align 8 +// CHECK6-NEXT: [[TMP43:%.*]] = load i32, i32* [[J_I]], align 4, !noalias !14 +// CHECK6-NEXT: store i32 [[TMP43]], i32* [[TMP42]], align 4 // CHECK6-NEXT: br label [[DOTOMP_OUTLINED__1_EXIT]] // CHECK6: .omp_outlined..1.exit: // CHECK6-NEXT: ret i32 0 |