[polly] fd229ca - [polly] Fix SCEVLoopAddRecRewriter to avoid invalid AddRecs.
Eli Friedman via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 1 09:51:17 PDT 2021
Author: Eli Friedman
Date: 2021-06-01T09:51:05-07:00
New Revision: fd229caa0138d296090c101655c82ca7da58ddd6
URL: https://github.com/llvm/llvm-project/commit/fd229caa0138d296090c101655c82ca7da58ddd6
DIFF: https://github.com/llvm/llvm-project/commit/fd229caa0138d296090c101655c82ca7da58ddd6.diff
LOG: [polly] Fix SCEVLoopAddRecRewriter to avoid invalid AddRecs.
When we're remapping an AddRec, the AddRec constructed by a partial
rewrite might not make sense. This triggers an assertion complaining
it's not loop-invariant.
Instead of constructing the partially rewritten AddRec, just skip
straight to calling evaluateAtIteration.
Testcase was automatically reduced using llvm-reduce, so it's a little
messy, but hopefully makes sense.
Differential Revision: https://reviews.llvm.org/D102959
Added:
polly/test/Isl/CodeGen/OpenMP/scev-rewriting.ll
Modified:
llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
llvm/lib/Analysis/ScalarEvolution.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h b/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
index 37e675f08afc3..ad0c74717090a 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h
@@ -401,6 +401,11 @@ class Type;
/// iteration number.
const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const;
+ /// Return the value of this chain of recurrences at the specified iteration
+ /// number. Takes an explicit list of operands to represent an AddRec.
+ static const SCEV *evaluateAtIteration(ArrayRef<const SCEV *> Operands,
+ const SCEV *It, ScalarEvolution &SE);
+
/// Return the number of iterations of this loop that produce
/// values in the specified constant range. Another way of
/// looking at this is that it returns the first iteration number
@@ -895,13 +900,10 @@ class Type;
Operands.push_back(visit(Op));
const Loop *L = Expr->getLoop();
- const SCEV *Res = SE.getAddRecExpr(Operands, L, Expr->getNoWrapFlags());
-
if (0 == Map.count(L))
- return Res;
+ return SE.getAddRecExpr(Operands, L, Expr->getNoWrapFlags());
- const SCEVAddRecExpr *Rec = cast<SCEVAddRecExpr>(Res);
- return Rec->evaluateAtIteration(Map[L], SE);
+ return SCEVAddRecExpr::evaluateAtIteration(Operands, Map[L], SE);
}
private:
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 84671f5530780..0d3d781d6ff46 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1025,16 +1025,23 @@ static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
/// where BC(It, k) stands for binomial coefficient.
const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
ScalarEvolution &SE) const {
- const SCEV *Result = getStart();
- for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
+ return evaluateAtIteration(makeArrayRef(op_begin(), op_end()), It, SE);
+}
+
+const SCEV *
+SCEVAddRecExpr::evaluateAtIteration(ArrayRef<const SCEV *> Operands,
+ const SCEV *It, ScalarEvolution &SE) {
+ assert(Operands.size() > 0);
+ const SCEV *Result = Operands[0];
+ for (unsigned i = 1, e = Operands.size(); i != e; ++i) {
// The computation is correct in the face of overflow provided that the
// multiplication is performed _after_ the evaluation of the binomial
// coefficient.
- const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
+ const SCEV *Coeff = BinomialCoefficient(It, i, SE, Result->getType());
if (isa<SCEVCouldNotCompute>(Coeff))
return Coeff;
- Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
+ Result = SE.getAddExpr(Result, SE.getMulExpr(Operands[i], Coeff));
}
return Result;
}
diff --git a/polly/test/Isl/CodeGen/OpenMP/scev-rewriting.ll b/polly/test/Isl/CodeGen/OpenMP/scev-rewriting.ll
new file mode 100644
index 0000000000000..13fffa3d9486d
--- /dev/null
+++ b/polly/test/Isl/CodeGen/OpenMP/scev-rewriting.ll
@@ -0,0 +1,56 @@
+; RUN: opt < %s -polly-vectorizer=polly -polly-parallel -polly-parallel-force -polly-process-unprofitable -polly-codegen -S | FileCheck %s
+; CHECK: define internal void @DoStringSort_polly_subfn
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnueabi"
+
+define void @DoStringSort() {
+bb:
+ br label %bb1
+
+bb1: ; preds = %bb1, %bb
+ %i = phi i32 [ 0, %bb ], [ %i2, %bb1 ]
+ %i2 = add i32 %i, 1
+ br i1 undef, label %bb1, label %bb3
+
+bb3: ; preds = %bb1
+ br i1 undef, label %bb6, label %bb4
+
+bb4: ; preds = %bb3
+ %i5 = bitcast i8* undef to i32*
+ br label %bb6
+
+bb6: ; preds = %bb4, %bb3
+ %i7 = phi i32* [ %i5, %bb4 ], [ undef, %bb3 ]
+ br i1 undef, label %bb21, label %bb8
+
+bb8: ; preds = %bb20, %bb6
+ %i9 = phi i32* [ %i7, %bb6 ], [ %i10, %bb20 ]
+ %i10 = getelementptr inbounds i32, i32* %i9, i32 %i2
+ br i1 undef, label %bb11, label %bb20
+
+bb11: ; preds = %bb8
+ br label %bb12
+
+bb12: ; preds = %bb11
+ br label %bb13
+
+bb13: ; preds = %bb12
+ br label %bb14
+
+bb14: ; preds = %bb14, %bb13
+ %i15 = phi i32 [ %i17, %bb14 ], [ 1, %bb13 ]
+ %i16 = getelementptr inbounds i32, i32* %i9, i32 %i15
+ store i32 undef, i32* %i16, align 4
+ %i17 = add i32 %i15, 1
+ %i18 = icmp eq i32 %i15, %i
+ br i1 %i18, label %bb19, label %bb14
+
+bb19: ; preds = %bb14
+ br label %bb20
+
+bb20: ; preds = %bb19, %bb8
+ br i1 undef, label %bb21, label %bb8
+
+bb21: ; preds = %bb20, %bb6
+ unreachable
+}
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