2011-01-01 19:54:22 +00:00
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; RUN: opt -basicaa -loop-idiom < %s -S | FileCheck %s
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implement enough of the memset inference algorithm to recognize and insert
memsets. This is still missing one important validity check, but this is enough
to compile stuff like this:
void test0(std::vector<char> &X) {
for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I)
*I = 0;
}
void test1(std::vector<int> &X) {
for (long i = 0, e = X.size(); i != e; ++i)
X[i] = 0x01010101;
}
With:
$ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc
to:
__Z5test0RSt6vectorIcSaIcEE: ## @_Z5test0RSt6vectorIcSaIcEE
## BB#0: ## %entry
subq $8, %rsp
movq (%rdi), %rax
movq 8(%rdi), %rsi
cmpq %rsi, %rax
je LBB0_2
## BB#1: ## %bb.nph
subq %rax, %rsi
movq %rax, %rdi
callq ___bzero
LBB0_2: ## %for.end
addq $8, %rsp
ret
...
__Z5test1RSt6vectorIiSaIiEE: ## @_Z5test1RSt6vectorIiSaIiEE
## BB#0: ## %entry
subq $8, %rsp
movq (%rdi), %rax
movq 8(%rdi), %rdx
subq %rax, %rdx
cmpq $4, %rdx
jb LBB1_2
## BB#1: ## %for.body.preheader
andq $-4, %rdx
movl $1, %esi
movq %rax, %rdi
callq _memset
LBB1_2: ## %for.end
addq $8, %rsp
ret
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122573 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-26 23:42:51 +00:00
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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"
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target triple = "x86_64-apple-darwin10.0.0"
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define void @test1(i8* %Base, i64 %Size) nounwind ssp {
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bb.nph: ; preds = %entry
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br label %for.body
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for.body: ; preds = %bb.nph, %for.body
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%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
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%I.0.014 = getelementptr i8* %Base, i64 %indvar
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store i8 0, i8* %I.0.014, align 1
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%indvar.next = add i64 %indvar, 1
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%exitcond = icmp eq i64 %indvar.next, %Size
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body, %entry
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ret void
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; CHECK: @test1
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; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 %Size, i32 1, i1 false)
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; CHECK-NOT: store
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}
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define void @test2(i32* %Base, i64 %Size) nounwind ssp {
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entry:
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%cmp10 = icmp eq i64 %Size, 0
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br i1 %cmp10, label %for.end, label %for.body
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for.body: ; preds = %entry, %for.body
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%i.011 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
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%add.ptr.i = getelementptr i32* %Base, i64 %i.011
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store i32 16843009, i32* %add.ptr.i, align 4
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%inc = add nsw i64 %i.011, 1
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%exitcond = icmp eq i64 %inc, %Size
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body, %entry
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ret void
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; CHECK: @test2
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; CHECK: br i1 %cmp10,
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; CHECK: %tmp = mul i64 %Size, 4
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; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base1, i8 1, i64 %tmp, i32 4, i1 false)
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; CHECK-NOT: store
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}
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2011-01-01 19:39:01 +00:00
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; This is a case where there is an extra may-aliased store in the loop, we can't
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; promote the memset.
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define void @test3(i32* %Base, i64 %Size, i8 *%MayAlias) nounwind ssp {
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entry:
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.011 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
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%add.ptr.i = getelementptr i32* %Base, i64 %i.011
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store i32 16843009, i32* %add.ptr.i, align 4
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store i8 42, i8* %MayAlias
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%inc = add nsw i64 %i.011, 1
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%exitcond = icmp eq i64 %inc, %Size
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %entry
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ret void
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; CHECK: @test3
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; CHECK-NOT: memset
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; CHECK: ret void
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}
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2011-01-01 19:54:22 +00:00
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;; TODO: We should be able to promote this memset. Not yet though.
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define void @test4(i8* %Base) nounwind ssp {
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bb.nph: ; preds = %entry
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%Base100 = getelementptr i8* %Base, i64 1000
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br label %for.body
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for.body: ; preds = %bb.nph, %for.body
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%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
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%I.0.014 = getelementptr i8* %Base, i64 %indvar
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store i8 0, i8* %I.0.014, align 1
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;; Store beyond the range memset, should be safe to promote.
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store i8 42, i8* %Base100
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%indvar.next = add i64 %indvar, 1
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%exitcond = icmp eq i64 %indvar.next, 100
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body, %entry
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ret void
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; CHECK-TODO: @test4
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; CHECK-TODO: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 100, i32 1, i1 false)
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; CHECK-TODO-NOT: store
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}
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