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llvm-mirror/test/Transforms/MemCpyOpt/memcpy-undef.ll
Nikita Popov 063c1a1b70 [MemCpyOpt] Handle read from lifetime.start with offset
This fixes a regression from the MemDep-based implementation:
MemDep completely ignores lifetime.start intrinsics that aren't
MustAlias -- this is probably unsound, but it does mean that the
MemDep based implementation successfully eliminated memcpy's from
lifetime.start if the memcpy happens at an offset, rather than
the base address of the alloca.

Add a special case for the case where the lifetime.start spans the
whole alloca (which is pretty much the only kind of lifetime.start
that frontends ever emit), as we don't need to figure out our exact
aliasing relationship in that case, the whole alloca is dead prior
to the call.

If this doesn't cover all practically relevant cases, then it
would be possible to make use of the recently added PartialAlias
clobber offsets to make this more precise.
2021-03-13 20:38:09 +01:00

155 lines
7.0 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=0 | FileCheck %s --check-prefixes=CHECK,NO-MSSA
; RUN: opt < %s -basic-aa -memcpyopt -S -enable-memcpyopt-memoryssa=1 -verify-memoryssa | FileCheck %s --check-prefixes=CHECK,MSSA
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.8.0"
%struct.foo = type { i8, [7 x i8], i32 }
; Check that the memcpy is removed.
define i32 @test1(%struct.foo* nocapture %foobie) nounwind noinline ssp uwtable {
; CHECK-LABEL: @test1(
; CHECK-NEXT: [[BLETCH_SROA_1:%.*]] = alloca [7 x i8], align 1
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[STRUCT_FOO:%.*]], %struct.foo* [[FOOBIE:%.*]], i64 0, i32 0
; CHECK-NEXT: store i8 98, i8* [[TMP1]], align 4
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds [[STRUCT_FOO]], %struct.foo* [[FOOBIE]], i64 0, i32 1, i64 0
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds [7 x i8], [7 x i8]* [[BLETCH_SROA_1]], i64 0, i64 0
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds [[STRUCT_FOO]], %struct.foo* [[FOOBIE]], i64 0, i32 2
; CHECK-NEXT: store i32 20, i32* [[TMP4]], align 4
; CHECK-NEXT: ret i32 undef
;
%bletch.sroa.1 = alloca [7 x i8], align 1
%1 = getelementptr inbounds %struct.foo, %struct.foo* %foobie, i64 0, i32 0
store i8 98, i8* %1, align 4
%2 = getelementptr inbounds %struct.foo, %struct.foo* %foobie, i64 0, i32 1, i64 0
%3 = getelementptr inbounds [7 x i8], [7 x i8]* %bletch.sroa.1, i64 0, i64 0
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %2, i8* %3, i64 7, i1 false)
%4 = getelementptr inbounds %struct.foo, %struct.foo* %foobie, i64 0, i32 2
store i32 20, i32* %4, align 4
ret i32 undef
}
; Check that the memcpy is removed.
define void @test2(i8* sret(i8) noalias nocapture %out, i8* %in) nounwind noinline ssp uwtable {
; CHECK-LABEL: @test2(
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 8, i8* [[IN:%.*]])
; CHECK-NEXT: ret void
;
call void @llvm.lifetime.start.p0i8(i64 8, i8* %in)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %out, i8* %in, i64 8, i1 false)
ret void
}
; Check that the memcpy is not removed.
define void @test3(i8* sret(i8) noalias nocapture %out, i8* %in) nounwind noinline ssp uwtable {
; CHECK-LABEL: @test3(
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 4, i8* [[IN:%.*]])
; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[OUT:%.*]], i8* [[IN]], i64 8, i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.lifetime.start.p0i8(i64 4, i8* %in)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %out, i8* %in, i64 8, i1 false)
ret void
}
; Check that the memcpy is not removed.
define void @test_lifetime_may_alias(i8* %lifetime, i8* %src, i8* %dst) {
; CHECK-LABEL: @test_lifetime_may_alias(
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 8, i8* [[LIFETIME:%.*]])
; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[DST:%.*]], i8* [[SRC:%.*]], i64 8, i1 false)
; CHECK-NEXT: ret void
;
call void @llvm.lifetime.start.p0i8(i64 8, i8* %lifetime)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 8, i1 false)
ret void
}
; lifetime.start on full alloca size, copy in range.
define void @test_lifetime_partial_alias_1(i8* noalias %dst) {
; CHECK-LABEL: @test_lifetime_partial_alias_1(
; CHECK-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; CHECK-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 16, i8* [[A_I8]])
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; CHECK-NEXT: ret void
;
%a = alloca [16 x i8]
%a.i8 = bitcast [16 x i8]* %a to i8*
call void @llvm.lifetime.start.p0i8(i64 16, i8* %a.i8)
%gep = getelementptr i8, i8* %a.i8, i64 8
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %gep, i64 8, i1 false)
ret void
}
; lifetime.start on full alloca size, copy out of range.
define void @test_lifetime_partial_alias_2(i8* noalias %dst) {
; CHECK-LABEL: @test_lifetime_partial_alias_2(
; CHECK-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; CHECK-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 16, i8* [[A_I8]])
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; CHECK-NEXT: ret void
;
%a = alloca [16 x i8]
%a.i8 = bitcast [16 x i8]* %a to i8*
call void @llvm.lifetime.start.p0i8(i64 16, i8* %a.i8)
%gep = getelementptr i8, i8* %a.i8, i64 8
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %gep, i64 16, i1 false)
ret void
}
; lifetime.start on part of alloca, copy in range.
define void @test_lifetime_partial_alias_3(i8* noalias %dst) {
; NO-MSSA-LABEL: @test_lifetime_partial_alias_3(
; NO-MSSA-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; NO-MSSA-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; NO-MSSA-NEXT: call void @llvm.lifetime.start.p0i8(i64 12, i8* [[A_I8]])
; NO-MSSA-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; NO-MSSA-NEXT: ret void
;
; MSSA-LABEL: @test_lifetime_partial_alias_3(
; MSSA-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; MSSA-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; MSSA-NEXT: call void @llvm.lifetime.start.p0i8(i64 12, i8* [[A_I8]])
; MSSA-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; MSSA-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[DST:%.*]], i8* [[GEP]], i64 4, i1 false)
; MSSA-NEXT: ret void
;
%a = alloca [16 x i8]
%a.i8 = bitcast [16 x i8]* %a to i8*
call void @llvm.lifetime.start.p0i8(i64 12, i8* %a.i8)
%gep = getelementptr i8, i8* %a.i8, i64 8
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %gep, i64 4, i1 false)
ret void
}
; lifetime.start on part of alloca, copy out of range.
define void @test_lifetime_partial_alias_4(i8* noalias %dst) {
; NO-MSSA-LABEL: @test_lifetime_partial_alias_4(
; NO-MSSA-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; NO-MSSA-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; NO-MSSA-NEXT: call void @llvm.lifetime.start.p0i8(i64 12, i8* [[A_I8]])
; NO-MSSA-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; NO-MSSA-NEXT: ret void
;
; MSSA-LABEL: @test_lifetime_partial_alias_4(
; MSSA-NEXT: [[A:%.*]] = alloca [16 x i8], align 1
; MSSA-NEXT: [[A_I8:%.*]] = bitcast [16 x i8]* [[A]] to i8*
; MSSA-NEXT: call void @llvm.lifetime.start.p0i8(i64 12, i8* [[A_I8]])
; MSSA-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[A_I8]], i64 8
; MSSA-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[DST:%.*]], i8* [[GEP]], i64 8, i1 false)
; MSSA-NEXT: ret void
;
%a = alloca [16 x i8]
%a.i8 = bitcast [16 x i8]* %a to i8*
call void @llvm.lifetime.start.p0i8(i64 12, i8* %a.i8)
%gep = getelementptr i8, i8* %a.i8, i64 8
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %gep, i64 8, i1 false)
ret void
}
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i1) nounwind
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) nounwind