[polly] r218758 - [RTC] Use the domain to split alias groups.
Johannes Doerfert
doerfert at cs.uni-saarland.de
Wed Oct 1 05:42:38 PDT 2014
Author: jdoerfert
Date: Wed Oct 1 07:42:37 2014
New Revision: 218758
URL: http://llvm.org/viewvc/llvm-project?rev=218758&view=rev
Log:
[RTC] Use the domain to split alias groups.
We use a parametric abstraction of the domain to split alias groups
if accesses cannot be executed under the same parameter evaluation.
The two test cases check that we can remove alias groups if the
pointers which might alias are never accessed under the same parameter
evaluation and that the minimal/maximal accesses are not global but
with regards to the parameter evaluation.
Differential Revision: http://reviews.llvm.org/D5436
Added:
polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_1.ll
polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_2.ll
Modified:
polly/trunk/lib/Analysis/ScopInfo.cpp
Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=218758&r1=218757&r2=218758&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
+++ polly/trunk/lib/Analysis/ScopInfo.cpp Wed Oct 1 07:42:37 2014
@@ -1191,6 +1191,12 @@ static int buildMinMaxAccess(__isl_take
return 0;
}
+static __isl_give isl_set *getAccessDomain(MemoryAccess *MA) {
+ isl_set *Domain = MA->getStatement()->getDomain();
+ Domain = isl_set_project_out(Domain, isl_dim_set, 0, isl_set_n_dim(Domain));
+ return isl_set_reset_tuple_id(Domain);
+}
+
bool Scop::buildAliasGroups(AliasAnalysis &AA) {
// To create sound alias checks we perform the following steps:
// o) Use the alias analysis and an alias set tracker to build alias sets
@@ -1198,6 +1204,10 @@ bool Scop::buildAliasGroups(AliasAnalysi
// o) For each alias set we then map the aliasing pointers back to the
// memory accesses we know, thus obtain groups of memory accesses which
// might alias.
+ // o) We divide each group based on the domains of the minimal/maximal
+ // accesses. That means two minimal/maximal accesses are only in a group
+ // if their access domains intersect, otherwise they are in different
+ // ones.
// o) We split groups such that they contain at most one read only base
// address.
// o) For each group with more than one base pointer we then compute minimal
@@ -1232,12 +1242,40 @@ bool Scop::buildAliasGroups(AliasAnalysi
AliasGroups.push_back(std::move(AG));
}
+ // Split the alias groups based on their domain.
+ for (unsigned u = 0; u < AliasGroups.size(); u++) {
+ AliasGroupTy NewAG;
+ AliasGroupTy &AG = AliasGroups[u];
+ AliasGroupTy::iterator AGI = AG.begin();
+ isl_set *AGDomain = getAccessDomain(*AGI);
+ while (AGI != AG.end()) {
+ MemoryAccess *MA = *AGI;
+ isl_set *MADomain = getAccessDomain(MA);
+ if (isl_set_is_disjoint(AGDomain, MADomain)) {
+ NewAG.push_back(MA);
+ AGI = AG.erase(AGI);
+ isl_set_free(MADomain);
+ } else {
+ AGDomain = isl_set_union(AGDomain, MADomain);
+ AGI++;
+ }
+ }
+ if (NewAG.size() > 1)
+ AliasGroups.push_back(std::move(NewAG));
+ isl_set_free(AGDomain);
+ }
+
DenseMap<const Value *, SmallPtrSet<MemoryAccess *, 8>> ReadOnlyPairs;
SmallPtrSet<const Value *, 4> NonReadOnlyBaseValues;
for (AliasGroupTy &AG : AliasGroups) {
NonReadOnlyBaseValues.clear();
ReadOnlyPairs.clear();
+ if (AG.size() < 2) {
+ AG.clear();
+ continue;
+ }
+
for (auto II = AG.begin(); II != AG.end();) {
Value *BaseAddr = (*II)->getBaseAddr();
if (HasWriteAccess.count(BaseAddr)) {
Added: polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_1.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_1.ll?rev=218758&view=auto
==============================================================================
--- polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_1.ll (added)
+++ polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_1.ll Wed Oct 1 07:42:37 2014
@@ -0,0 +1,56 @@
+; RUN: opt %loadPolly -polly-code-generator=isl -polly-scops -analyze < %s | FileCheck %s
+;
+; Check that there is no alias group because we either access A or B never both.
+;
+; CHECK: Alias Groups (0):
+;
+; void jd(int b, int *A, int *B) {
+; for (int i = 0; i < 1024; i++) {
+; if (b)
+; A[i] = A[i - 1];
+; else
+; B[i] = B[i - 1];
+; }
+; }
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @jd(i32 %b, i32* %A, i32* %B) {
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.inc, %entry
+ %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
+ %exitcond = icmp ne i64 %indvars.iv, 1024
+ br i1 %exitcond, label %for.body, label %for.end
+
+for.body: ; preds = %for.cond
+ %tobool = icmp eq i32 %b, 0
+ br i1 %tobool, label %if.else, label %if.then
+
+if.then: ; preds = %for.body
+ %tmp = add nsw i64 %indvars.iv, -1
+ %arrayidx = getelementptr inbounds i32* %A, i64 %tmp
+ %tmp3 = load i32* %arrayidx, align 4
+ %arrayidx2 = getelementptr inbounds i32* %A, i64 %indvars.iv
+ store i32 %tmp3, i32* %arrayidx2, align 4
+ br label %if.end
+
+if.else: ; preds = %for.body
+ %tmp4 = add nsw i64 %indvars.iv, -1
+ %arrayidx5 = getelementptr inbounds i32* %B, i64 %tmp4
+ %tmp5 = load i32* %arrayidx5, align 4
+ %arrayidx7 = getelementptr inbounds i32* %B, i64 %indvars.iv
+ store i32 %tmp5, i32* %arrayidx7, align 4
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ br label %for.inc
+
+for.inc: ; preds = %if.end
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %for.cond
+
+for.end: ; preds = %for.cond
+ ret void
+}
Added: polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_2.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_2.ll?rev=218758&view=auto
==============================================================================
--- polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_2.ll (added)
+++ polly/trunk/test/ScopInfo/aliasing_conditional_alias_groups_2.ll Wed Oct 1 07:42:37 2014
@@ -0,0 +1,55 @@
+; RUN: opt %loadPolly -polly-code-generator=isl -polly-scops -analyze < %s | FileCheck %s
+;
+; Check that we create two alias groups since the mininmal/maximal accesses
+; depend on %b.
+;
+; CHECK: Alias Groups (2):
+;
+; void jd(int b, int *A, int *B) {
+; for (int i = 0; i < 1024; i++) {
+; if (b)
+; A[i] = B[5];
+; else
+; B[i] = A[7];
+; }
+; }
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @jd(i32 %b, i32* %A, i32* %B) {
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.inc, %entry
+ %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
+ %exitcond = icmp ne i64 %indvars.iv, 1024
+ br i1 %exitcond, label %for.body, label %for.end
+
+for.body: ; preds = %for.cond
+ %tobool = icmp eq i32 %b, 0
+ br i1 %tobool, label %if.else, label %if.then
+
+if.then: ; preds = %for.body
+ %arrayidx = getelementptr inbounds i32* %B, i64 5
+ %tmp = load i32* %arrayidx, align 4
+ %arrayidx1 = getelementptr inbounds i32* %A, i64 %indvars.iv
+ store i32 %tmp, i32* %arrayidx1, align 4
+ br label %if.end
+
+if.else: ; preds = %for.body
+ %arrayidx2 = getelementptr inbounds i32* %A, i64 7
+ %tmp1 = load i32* %arrayidx2, align 4
+ %arrayidx4 = getelementptr inbounds i32* %B, i64 %indvars.iv
+ store i32 %tmp1, i32* %arrayidx4, align 4
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ br label %for.inc
+
+for.inc: ; preds = %if.end
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ br label %for.cond
+
+for.end: ; preds = %for.cond
+ ret void
+}
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