wangtao
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

[ScopInfo] Make memset etc. affine where possible. 

We don't actually check whether a MemoryAccess is affine in very many
places, but one important one is in checks for aliasing.

Differential Revision: https://reviews.llvm.org/D25706

llvm-svn: 285746
This commit is contained in:
Eli Friedman 2016-11-01 20:53:11 +00:00
parent 6768285dcc
commit b9c6f01a81
3 changed files with 74 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
polly/lib/Analysis/ScopBuilder.cpp
View File

@ -275,8 +275,9 @@ bool ScopBuilder::buildAccessMemIntrinsic(MemAccInst Inst, Loop *L) {
assert(DestPtrSCEV);
DestAccFunc = SE.getMinusSCEV(DestAccFunc, DestPtrSCEV);
addArrayAccess(Inst, MemoryAccess::MUST_WRITE, DestPtrSCEV->getValue(),
IntegerType::getInt8Ty(DestPtrVal->getContext()), false,
{DestAccFunc, LengthVal}, {nullptr}, Inst.getValueOperand());
IntegerType::getInt8Ty(DestPtrVal->getContext()),
LengthIsAffine, {DestAccFunc, LengthVal}, {nullptr},
Inst.getValueOperand());
auto *MemTrans = dyn_cast<MemTransferInst>(MemIntr);
if (!MemTrans)
@ -296,8 +297,9 @@ bool ScopBuilder::buildAccessMemIntrinsic(MemAccInst Inst, Loop *L) {
assert(SrcPtrSCEV);
SrcAccFunc = SE.getMinusSCEV(SrcAccFunc, SrcPtrSCEV);
addArrayAccess(Inst, MemoryAccess::READ, SrcPtrSCEV->getValue(),
IntegerType::getInt8Ty(SrcPtrVal->getContext()), false,
{SrcAccFunc, LengthVal}, {nullptr}, Inst.getValueOperand());
IntegerType::getInt8Ty(SrcPtrVal->getContext()),
LengthIsAffine, {SrcAccFunc, LengthVal}, {nullptr},
Inst.getValueOperand());
return true;
}

10
polly/lib/Analysis/ScopInfo.cpp
View File

@ -816,10 +816,14 @@ void MemoryAccess::buildAccessRelation(const ScopArrayInfo *SAI) {
isl_ctx *Ctx = isl_id_get_ctx(Id);
isl_id *BaseAddrId = SAI->getBasePtrId();
if (!isAffine()) {
if (isa<MemIntrinsic>(getAccessInstruction()))
buildMemIntrinsicAccessRelation();
if (getAccessInstruction() && isa<MemIntrinsic>(getAccessInstruction())) {
buildMemIntrinsicAccessRelation();
AccessRelation =
isl_map_set_tuple_id(AccessRelation, isl_dim_out, BaseAddrId);
return;
}
if (!isAffine()) {
// We overapproximate non-affine accesses with a possible access to the
// whole array. For read accesses it does not make a difference, if an
// access must or may happen. However, for write accesses it is important to

74
polly/test/ScopInfo/aliasing_with_non_affine_access.ll
View File

@ -1,18 +1,16 @@
; RUN: opt %loadPolly -analyze -polly-scops < %s | FileCheck %s
; RUN: opt %loadPolly -analyze -polly-scops -pass-remarks-analysis="polly-scops" 2>&1 < %s | FileCheck %s --check-prefix=REMARK
; RUN: opt %loadPolly -analyze -polly-ast -polly-process-unprofitable -polly-allow-nonaffine < %s | FileCheck %s
;
; This test case has a non-affine access (the memset call) that aliases with
; other accesses. Thus, we bail out.
; @test1
; Make sure we generate the correct aliasing check for a fixed-size memset operation.
; CHECK: if (1 && (&MemRef_0[15] <= &MemRef_1[0] || &MemRef_1[32] <= &MemRef_0[14]))
;
; CHECK-NOT: Statements
; @test2
; Make sure we generate the correct aliasing check for a variable-size memset operation.
; CHECK: if (1 && (&MemRef_0[15] <= &MemRef_1[0] || &MemRef_1[n] <= &MemRef_0[14]))
;
; REMARK: remark: <unknown>:0:0: SCoP begins here.
; REMARK-NEXT: remark: <unknown>:0:0: Possibly aliasing pointer, use restrict keyword.
; REMARK-NEXT: remark: <unknown>:0:0: Possibly aliasing pointer, use restrict keyword.
; REMARK-NEXT: remark: <unknown>:0:0: No-aliasing assumption: { : 1 = 0 }
; REMARK-NEXT: remark: <unknown>:0:0: SCoP ends here but was dismissed.
; @test3
; We can't do anything interesting with a non-affine memset; just make sure it doesn't crash.
;
; ModuleID = 'bugpoint-reduced-simplified.bc'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
%struct.info = type { i32, %struct.ctr*, i32, %struct.ord*, %struct.ctr*, i32, i8*, i32, i32, double }
@ -22,8 +20,7 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Function Attrs: argmemonly nounwind
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) #0
; Function Attrs: nounwind uwtable
define void @bestVirtualIndex(%struct.info** %ppIdxInfo) {
define void @test1(%struct.info** %ppIdxInfo) {
entry:
%0 = load %struct.info*, %struct.info** %ppIdxInfo, align 8
br label %if.end125
@ -46,4 +43,55 @@ if.end149: ; preds = %if.then148, %for.en
unreachable
}
define void @test2(%struct.info** %ppIdxInfo, i64 %n) {
entry:
%0 = load %struct.info*, %struct.info** %ppIdxInfo, align 8
br label %if.end125
if.end125: ; preds = %entry
%1 = load %struct.ctr*, %struct.ctr** undef, align 8
br label %for.end143
for.end143: ; preds = %if.end125
%2 = bitcast %struct.ctr* %1 to i8*
tail call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 %n, i32 4, i1 false)
%needToFreeIdxStr = getelementptr inbounds %struct.info, %struct.info* %0, i64 0, i32 7
%3 = load i32, i32* %needToFreeIdxStr, align 8
br i1 false, label %if.end149, label %if.then148
if.then148: ; preds = %for.end143
br label %if.end149
if.end149: ; preds = %if.then148, %for.end143
unreachable
}
define i32 @test3(i32* %x, i32 %n) {
entry:
br label %entry.split
entry.split: ; preds = %entry
%conv = sext i32 %n to i64
%cmp8 = icmp sgt i32 %n, 0
br i1 %cmp8, label %for.body.lr.ph, label %for.cond.cleanup
for.body.lr.ph: ; preds = %entry.split
%0 = bitcast i32* %x to i8*
br label %for.body
for.cond.cleanup: ; preds = %for.body, %entry.split
ret i32 0
for.body: ; preds = %for.body, %for.body.lr.ph
%i.09 = phi i64 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
%mul = mul nsw i64 %i.09, %i.09
tail call void @llvm.memset.p0i8.i64(i8* %0, i8 0, i64 %mul, i32 4, i1 false)
%add = add nuw nsw i64 %i.09, 1000
%arrayidx = getelementptr inbounds i32, i32* %x, i64 %add
store i32 5, i32* %arrayidx, align 4
%inc = add nuw nsw i64 %i.09, 1
%exitcond = icmp eq i64 %inc, %conv
br i1 %exitcond, label %for.cond.cleanup, label %for.body
}
attributes #0 = { argmemonly nounwind }