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llvm-6502/test/Transforms/LoopIdiom/basic.ll
Chris Lattner e41d3c015c Teach loop-idiom to turn a loop containing a memset into a larger memset 
when safe.

The testcase is basically this nested loop:
void foo(char *X) {
  for (int i = 0; i != 100; ++i) 
    for (int j = 0; j != 100; ++j)
      X[j+i*100] = 0;
}

which gets turned into a single memset now.  clang -O3 doesn't optimize
this yet though due to a phase ordering issue I haven't analyzed yet.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122806 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-04 07:46:33 +00:00

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; RUN: opt -basicaa -loop-idiom < %s -S | FileCheck %s
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"
target triple = "x86_64-apple-darwin10.0.0"
define void @test1(i8* %Base, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
store i8 0, i8* %I.0.014, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test1
; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 %Size, i32 1, i1 false)
; CHECK-NOT: store
}
; This is a loop that was rotated but where the blocks weren't merged. This
; shouldn't perturb us.
define void @test1a(i8* %Base, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body.cont ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
store i8 0, i8* %I.0.014, align 1
%indvar.next = add i64 %indvar, 1
br label %for.body.cont
for.body.cont:
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test1a
; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 %Size, i32 1, i1 false)
; CHECK-NOT: store
}
define void @test2(i32* %Base, i64 %Size) nounwind ssp {
entry:
%cmp10 = icmp eq i64 %Size, 0
br i1 %cmp10, label %for.end, label %for.body
for.body: ; preds = %entry, %for.body
%i.011 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
%add.ptr.i = getelementptr i32* %Base, i64 %i.011
store i32 16843009, i32* %add.ptr.i, align 4
%inc = add nsw i64 %i.011, 1
%exitcond = icmp eq i64 %inc, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test2
; CHECK: br i1 %cmp10,
; CHECK: %tmp = mul i64 %Size, 4
; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base1, i8 1, i64 %tmp, i32 4, i1 false)
; CHECK-NOT: store
}
; This is a case where there is an extra may-aliased store in the loop, we can't
; promote the memset.
define void @test3(i32* %Base, i64 %Size, i8 *%MayAlias) nounwind ssp {
entry:
br label %for.body
for.body: ; preds = %entry, %for.body
%i.011 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
%add.ptr.i = getelementptr i32* %Base, i64 %i.011
store i32 16843009, i32* %add.ptr.i, align 4
store i8 42, i8* %MayAlias
%inc = add nsw i64 %i.011, 1
%exitcond = icmp eq i64 %inc, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %entry
ret void
; CHECK: @test3
; CHECK-NOT: memset
; CHECK: ret void
}
;; TODO: We should be able to promote this memset. Not yet though.
define void @test4(i8* %Base) nounwind ssp {
bb.nph: ; preds = %entry
%Base100 = getelementptr i8* %Base, i64 1000
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
store i8 0, i8* %I.0.014, align 1
;; Store beyond the range memset, should be safe to promote.
store i8 42, i8* %Base100
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, 100
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK-TODO: @test4
; CHECK-TODO: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 100, i32 1, i1 false)
; CHECK-TODO-NOT: store
}
; This can't be promoted: the memset is a store of a loop variant value.
define void @test5(i8* %Base, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
%V = trunc i64 %indvar to i8
store i8 %V, i8* %I.0.014, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test5
; CHECK-NOT: memset
; CHECK: ret void
}
;; memcpy formation
define void @test6(i64 %Size) nounwind ssp {
bb.nph:
%Base = alloca i8, i32 10000
%Dest = alloca i8, i32 10000
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
%DestI = getelementptr i8* %Dest, i64 %indvar
%V = load i8* %I.0.014, align 1
store i8 %V, i8* %DestI, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test6
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %Dest, i8* %Base, i64 %Size, i32 1, i1 false)
; CHECK-NOT: store
; CHECK: ret void
}
; This is a loop that was rotated but where the blocks weren't merged. This
; shouldn't perturb us.
define void @test7(i8* %Base, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body.cont ]
br label %for.body.cont
for.body.cont:
%I.0.014 = getelementptr i8* %Base, i64 %indvar
store i8 0, i8* %I.0.014, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test7
; CHECK: call void @llvm.memset.p0i8.i64(i8* %Base, i8 0, i64 %Size, i32 1, i1 false)
; CHECK-NOT: store
}
; This is a loop should not be transformed, it only executes one iteration.
define void @test8(i64* %Ptr, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%PI = getelementptr i64* %Ptr, i64 %indvar
store i64 0, i64 *%PI
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, 1
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test8
; CHECK: store i64 0, i64* %PI
}
declare i8* @external(i8*)
;; This cannot be transformed into a memcpy, because the read-from location is
;; mutated by the loop.
define void @test9(i64 %Size) nounwind ssp {
bb.nph:
%Base = alloca i8, i32 10000
%Dest = alloca i8, i32 10000
%BaseAlias = call i8* @external(i8* %Base)
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%I.0.014 = getelementptr i8* %Base, i64 %indvar
%DestI = getelementptr i8* %Dest, i64 %indvar
%V = load i8* %I.0.014, align 1
store i8 %V, i8* %DestI, align 1
;; This store can clobber the input.
store i8 4, i8* %BaseAlias
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, %Size
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test9
; CHECK-NOT: llvm.memcpy
; CHECK: ret void
}
; Two dimensional nested loop should be promoted to one big memset.
define void @test10(i8* %X) nounwind ssp {
entry:
br label %bb.nph
bb.nph: ; preds = %entry, %for.inc10
%i.04 = phi i32 [ 0, %entry ], [ %inc12, %for.inc10 ]
br label %for.body5
for.body5: ; preds = %for.body5, %bb.nph
%j.02 = phi i32 [ 0, %bb.nph ], [ %inc, %for.body5 ]
%mul = mul nsw i32 %i.04, 100
%add = add nsw i32 %j.02, %mul
%idxprom = sext i32 %add to i64
%arrayidx = getelementptr inbounds i8* %X, i64 %idxprom
store i8 0, i8* %arrayidx, align 1
%inc = add nsw i32 %j.02, 1
%cmp4 = icmp eq i32 %inc, 100
br i1 %cmp4, label %for.inc10, label %for.body5
for.inc10: ; preds = %for.body5
%inc12 = add nsw i32 %i.04, 1
%cmp = icmp eq i32 %inc12, 100
br i1 %cmp, label %for.end13, label %bb.nph
for.end13: ; preds = %for.inc10
ret void
; CHECK: @test10
; CHECK: entry:
; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* %X, i8 0, i64 10000, i32 1, i1 false)
; CHECK-NOT: store
; CHECK: ret void
}
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