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[CodeGen] Add invalidation of the loop SCEVs after merge block generation.

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The SCEVs of loops surrounding the escape users of a merge blocks are
forgotten, so that loop trip counts based on old values can be revoked.

This fixes llvm.org//PR32536

Contributed-by: Baranidharan Mohan <mbdharan@gmail.com>

Differential Revision: https://reviews.llvm.org/D33195

llvm-svn: 303561
This commit is contained in:
Michael Kruse 2017-05-22 15:36:53 +00:00
parent e00da22ef3
commit 1aad76c18f
3 changed files with 85 additions and 2 deletions
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5
polly/include/polly/CodeGen/BlockGenerators.h
View File

@ -580,8 +580,9 @@ protected:
/// Invalidate the scalar evolution expressions for a scop.
///
/// This function invalidates the scalar evolution results for all
/// instructions that are part of a given scop. This is necessary to ensure
/// that later scops do not obtain scalar evolution expressions that reference
/// instructions that are part of a given scop, and the loops
/// surrounding the users of merge blocks. This is necessary to ensure that
/// later scops do not obtain scalar evolution expressions that reference
/// values that earlier dominated the later scop, but have been moved in the
/// conditional part of an earlier scop and consequently do not any more
/// dominate the later scop.

12
polly/lib/CodeGen/BlockGenerators.cpp
View File

@ -858,6 +858,18 @@ void BlockGenerator::invalidateScalarEvolution(Scop &S) {
SE.forgetValue(&Inst);
else
llvm_unreachable("Unexpected statement type found");
// Invalidate SCEV of loops surrounding the EscapeUsers.
for (const auto &EscapeMapping : EscapeMap) {
const EscapeUserVectorTy &EscapeUsers = EscapeMapping.second.second;
for (Instruction *EUser : EscapeUsers) {
if (Loop *L = LI.getLoopFor(EUser->getParent()))
while (L) {
SE.forgetLoop(L);
L = L->getParentLoop();
}
}
}
}
void BlockGenerator::finalizeSCoP(Scop &S) {

70
polly/test/Isl/CodeGen/two-scops-in-row-invalidate-scevs.ll Normal file
View File

@ -0,0 +1,70 @@
; RUN: opt %loadPolly -polly-codegen -S < %s | FileCheck %s
;
; CHECK-LABEL: for.cond:
; CHECK: %num.0 = phi i32 [ %add, %for.body15 ], [ 0, %for.cond.pre_entry_bb ]
; CHECK: br i1 false, label %for.body15, label %for.end22
; CHECK-LABEL: polly.merge_new_and_old:
; CHECK: %num.0.merge = phi i32 [ %num.0.final_reload, %polly.exiting ], [ %num.0, %for.end22 ]
; CHECK: br label %for.end44
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
define void @func(i32* %p) {
entry:
%counters = alloca [64 x i32], align 16
%lenCounters = alloca [17 x i32], align 16
br label %for.cond
for.cond: ; preds = %for.body15, %for.cond
%num.0 = phi i32 [ 0, %entry ], [ %add, %for.body15 ]
br i1 false, label %for.body15, label %for.end22
for.body15: ; preds = %for.cond
%arrayidx17 = getelementptr inbounds [64 x i32], [64 x i32]* %counters, i64 0, i64 0
%0 = load i32, i32* %arrayidx17, align 4
%add = add i32 %num.0, %0
br label %for.cond
for.end22: ; preds = %for.cond
br label %for.end44
for.end44: ; preds = %for.end22
br i1 undef, label %if.then50, label %if.end67
if.then50: ; preds = %for.end44
br label %cleanup
if.end67: ; preds = %for.end44
br label %do.body
do.body: ; preds = %cond.end109, %if.end67
%e.0 = phi i32 [ 0, %if.end67 ], [ %inc128, %cond.end109 ]
br label %cond.end109
cond.end109: ; preds = %do.body
%idxprom122 = zext i32 %e.0 to i64
%arrayidx123 = getelementptr inbounds i32, i32* %p, i64 %idxprom122
%inc128 = add i32 %e.0, 1
%sub129 = sub i32 %num.0, %inc128
%cmp130 = icmp ugt i32 %sub129, 1
br i1 %cmp130, label %do.body, label %do.end
do.end: ; preds = %cond.end109
%1 = load i32, i32* %arrayidx123, align 4
%arrayidx142 = getelementptr inbounds [17 x i32], [17 x i32]* %lenCounters, i64 0, i64 1
store i32 2, i32* %arrayidx142, align 4
br label %for.cond201
for.cond201: ; preds = %for.body204, %do.end
br i1 undef, label %for.body204, label %for.end214
for.body204: ; preds = %for.cond201
br label %for.cond201
for.end214: ; preds = %for.cond201
br label %cleanup
cleanup: ; preds = %for.end214, %if.then50
ret void
}