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author | Francis Visoiu Mistrih <francisvm@yahoo.com> | 2019-10-08 22:10:38 +0000 |
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committer | Francis Visoiu Mistrih <francisvm@yahoo.com> | 2019-10-08 22:10:38 +0000 |
commit | b7e1c7cd95dcb7cc3ab6777f237326c47fae5165 (patch) | |
tree | f6ae105448a351e083d50946b009ad925fa66418 /test/CodeGen/aarch64-byval-temp.c | |
parent | 54b0fb8af38294b3571b798ce0053f79bb6e0d27 (diff) | |
download | clang-b7e1c7cd95dcb7cc3ab6777f237326c47fae5165.tar.gz |
[IRGen] Emit lifetime markers for temporary struct allocas
When passing arguments using temporary allocas, we need to add the
appropriate lifetime markers so that the stack coloring passes can
re-use the stack space.
This patch keeps track of all the lifetime.start calls emited before the
codegened call, and adds the corresponding lifetime.end calls after the
call.
Differential Revision: https://reviews.llvm.org/D68611
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374126 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/CodeGen/aarch64-byval-temp.c')
-rw-r--r-- | test/CodeGen/aarch64-byval-temp.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/test/CodeGen/aarch64-byval-temp.c b/test/CodeGen/aarch64-byval-temp.c new file mode 100644 index 0000000000..f70f605e24 --- /dev/null +++ b/test/CodeGen/aarch64-byval-temp.c @@ -0,0 +1,89 @@ +// RUN: %clang_cc1 -emit-llvm -triple arm64-- -o - %s -O0 | FileCheck %s --check-prefix=CHECK-O0 +// RUN: %clang_cc1 -emit-llvm -disable-llvm-optzns -triple arm64-- -o - %s -O3 | FileCheck %s --check-prefix=CHECK-O3 + +struct large { + void* pointers[8]; +}; + +void pass_large(struct large); + +// For arm64, we don't use byval to pass structs but instead we create +// temporary allocas. +// +// Make sure we generate the appropriate lifetime markers for the temporary +// allocas so that the optimizer can re-use stack slots if possible. +void example() { + struct large l = {0}; + pass_large(l); + pass_large(l); +} +// CHECK-O0-LABEL: define void @example( +// The alloca for the struct on the stack. +// CHECK-O0: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// The alloca for the temporary stack space that we use to pass the argument. +// CHECK-O0-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// Another one to pass the argument to the second function call. +// CHECK-O0-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// First, memset `l` to 0. +// CHECK-O0-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O0-NEXT: call void @llvm.memset.p0i8.i64(i8* align 8 %[[bitcastl]], i8 0, i64 64, i1 false) +// Then, memcpy `l` to the temporary stack space. +// CHECK-O0-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8* +// CHECK-O0-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O0-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false) +// Finally, call using a pointer to the temporary stack space. +// CHECK-O0-NEXT: call void @pass_large(%struct.large* %[[byvaltemp]]) +// Now, do the same for the second call, using the second temporary alloca. +// CHECK-O0-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8* +// CHECK-O0-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O0-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false) +// CHECK-O0-NEXT: call void @pass_large(%struct.large* %[[byvaltemp1]]) +// CHECK-O0-NEXT: ret void +// +// At O3, we should have lifetime markers to help the optimizer re-use the temporary allocas. +// +// CHECK-O3-LABEL: define void @example( +// The alloca for the struct on the stack. +// CHECK-O3: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// The alloca for the temporary stack space that we use to pass the argument. +// CHECK-O3-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// Another one to pass the argument to the second function call. +// CHECK-O3-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8 +// +// Mark the start of the lifetime for `l` +// CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastl]]) +// +// First, memset `l` to 0. +// CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O3-NEXT: call void @llvm.memset.p0i8.i64(i8* align 8 %[[bitcastl]], i8 0, i64 64, i1 false) +// +// Lifetime of the first temporary starts here and ends right after the call. +// CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastbyvaltemp]]) +// +// Then, memcpy `l` to the temporary stack space. +// CHECK-O3-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8* +// CHECK-O3-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O3-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false) +// Finally, call using a pointer to the temporary stack space. +// CHECK-O3-NEXT: call void @pass_large(%struct.large* %[[byvaltemp]]) +// +// The lifetime of the temporary used to pass a pointer to the struct ends here. +// CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp]] to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastbyvaltemp]]) +// +// Now, do the same for the second call, using the second temporary alloca. +// CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0i8(i64 64, i8* %[[bitcastbyvaltemp]]) +// CHECK-O3-NEXT: %[[src:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8* +// CHECK-O3-NEXT: %[[dst:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[l]] to i8* +// CHECK-O3-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %[[src]], i8* align 8 %[[dst]], i64 64, i1 false) +// CHECK-O3-NEXT: call void @pass_large(%struct.large* %[[byvaltemp1]]) +// CHECK-O3-NEXT: %[[bitcastbyvaltemp:[0-9A-Za-z-]+]] = bitcast %struct.large* %[[byvaltemp1]] to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastbyvaltemp]]) +// +// Mark the end of the lifetime of `l`. +// CHECK-O3-NEXT: %[[bitcastl:[0-9A-Za-z-]+]] = bitcast %struct.large* %l to i8* +// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0i8(i64 64, i8* %[[bitcastl]]) +// CHECK-O3-NEXT: ret void |