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[Polly][OpTree] Fix mid-processing change of access kind.

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Operand tree forwarding can cause the change of an access kind; in
particular change from a scalar kind to an array kind if the scalar
dependency is not necessary. Such an access cannot and doesn't need to
be forwarded anymore.

Fixes llvm.org/PR48034
This commit is contained in:
Michael Kruse 2020-11-11 16:14:48 -06:00
parent c1cf51e777
commit c8a0e27cfb
2 changed files with 57 additions and 6 deletions
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9
polly/lib/Transform/ForwardOpTree.cpp
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@ -979,17 +979,14 @@ public:
// Because we are modifying the MemoryAccess list, collect them first to
// avoid iterator invalidation.
SmallVector<MemoryAccess *, 16> Accs;
for (MemoryAccess *RA : Stmt) {
SmallVector<MemoryAccess *, 16> Accs(Stmt.begin(), Stmt.end());
for (MemoryAccess *RA : Accs) {
if (!RA->isRead())
continue;
if (!RA->isLatestScalarKind())
continue;
Accs.push_back(RA);
}
for (MemoryAccess *RA : Accs) {
if (tryForwardTree(RA)) {
Modified = true;
StmtModified = true;

54
polly/test/ForwardOpTree/changed-kind.ll Normal file
View File

@ -0,0 +1,54 @@
; RUN: opt %loadPolly -polly-optree -analyze < %s | FileCheck %s -match-full-lines
; In the code below, %0 is known to be equal to the content of @c (constant 0).
; Thus, in order to save a scalar dependency, forward-optree replaces
; the use of %0 in Stmt_lor_end93 by a load from @c by changing the
; access find from a scalar access to a array accesses.
; llvm.org/PR48034 decribes a crash caused by the mid-processing change.
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@c = external dso_local global i64, align 8
define void @func() {
entry:
br label %lor.end
while.cond.loopexit:
%conv102.le = trunc i64 %xor101 to i8
ret void
lor.end:
%tobool72.not = icmp eq i64 0, 0
br i1 %tobool72.not, label %lor.rhs87, label %lor.end.thread
lor.end.thread:
br label %lor.rhs87
lor.rhs87:
%0 = phi i64 [ 0, %lor.end.thread ], [ 0, %lor.end ]
store i64 %0, i64* @c, align 8
%neg79 = xor i64 %0, -1
br label %lor.end93
lor.end93:
%tobool93 = icmp ne i64 undef, 0
%conv95 = zext i1 %tobool93 to i64
%and100 = and i64 %conv95, undef
%xor101 = xor i64 %and100, %neg79
%xor103 = xor i64 %0, %conv95
br label %while.cond.loopexit
}
; CHECK: Statistics {
; CHECK: Reloads: 1
; CHECK: }
; CHECK: After statements {
; CHECK: Stmt_lor_end93
; CHECK-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
; CHECK-NEXT: { Stmt_lor_end93[] -> MemRef3[] };
; CHECK-NEXT: new: { Stmt_lor_end93[] -> MemRef_c[0] };
; CHECK: }