[PATCH] D80973: [LSR][SCEVExpander] Avoid blind cast 'Factor' to SCEVConstant in FactorOutConstant.
Huihui Zhang via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 1 21:05:27 PDT 2020
huihuiz created this revision.
huihuiz added reviewers: efriedma, sdesmalen, sanjoy.google, mkazantsev.
huihuiz added a project: LLVM.
Herald added subscribers: javed.absar, hiraditya.
In SCEVExpander FactorOutConstant(), when GEP indexing into/over scalable vector,
it is legal for the 'Factor' in a MulExpr to be the size of a scalable vector
instead of a compile-time constant.
Current upstream crash with the test attached.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D80973
Files:
llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
llvm/test/Transforms/LoopStrengthReduce/vscale-factor-out-constant.ll
Index: llvm/test/Transforms/LoopStrengthReduce/vscale-factor-out-constant.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopStrengthReduce/vscale-factor-out-constant.ll
@@ -0,0 +1,46 @@
+; RUN: opt -S -loop-reduce < %s | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+; This test check SCEVExpander FactorOutConstant() is not crashing with blind cast Factor to SCEVConstant.
+
+; CHECK-LABEL: test
+define void @test(i32* %a, i32 %v, i64 %n) {
+entry:
+ %scalar_vector = alloca <vscale x 4 x i32>, align 16
+ %num_elm = call i64 @llvm.aarch64.sve.cntw(i32 31)
+ %scalar_count = and i64 %num_elm, -4
+ br label %loop_header
+
+exit:
+ ret void
+
+loop_header:
+ %indvar = phi i64 [ 0, %entry ], [ %indvar_next, %for_loop ]
+ %gep_a_0 = getelementptr i32, i32* %a, i64 0
+ %gep_vec_0 = getelementptr inbounds <vscale x 4 x i32>, <vscale x 4 x i32>* %scalar_vector, i64 0, i64 0
+ br label %scalar_loop
+
+scalar_loop:
+ %gep_vec = phi i32* [ %gep_vec_0, %loop_header ], [ %gep_vec_inc, %scalar_loop ]
+ %scalar_iv = phi i64 [ 0, %loop_header ], [ %scalar_iv_next, %scalar_loop ]
+ store i32 %v, i32* %gep_vec, align 4
+ %scalar_iv_next = add i64 %scalar_iv, 1
+ %gep_vec_inc = getelementptr i32, i32* %gep_vec, i64 1
+ %scalar_exit = icmp eq i64 %scalar_iv_next, %scalar_count
+ br i1 %scalar_exit, label %for_loop, label %scalar_loop
+
+for_loop:
+ %vector = load <vscale x 4 x i32>, <vscale x 4 x i32>* %scalar_vector, align 16
+ %gep_a = getelementptr i32, i32* %gep_a_0, i64 %indvar
+ %vector_ptr = bitcast i32* %gep_a to <vscale x 4 x i32>*
+ call void @llvm.masked.store.nxv4i32.p0nxv4i32(<vscale x 4 x i32> %vector, <vscale x 4 x i32>* %vector_ptr, i32 4, <vscale x 4 x i1> undef)
+ %indvar_next = add nsw i64 %indvar, %scalar_count
+ %exit_cond = icmp eq i64 %indvar_next, %n
+ br i1 %exit_cond, label %exit, label %loop_header
+}
+
+declare i64 @llvm.aarch64.sve.cntw(i32 immarg)
+
+declare void @llvm.masked.store.nxv4i32.p0nxv4i32(<vscale x 4 x i32>, <vscale x 4 x i32>*, i32 immarg, <vscale x 4 x i1>)
Index: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -287,14 +287,14 @@
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
// Size is known, check if there is a constant operand which is a multiple
// of the given factor. If so, we can factor it.
- const SCEVConstant *FC = cast<SCEVConstant>(Factor);
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
- if (!C->getAPInt().srem(FC->getAPInt())) {
- SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
- NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
- S = SE.getMulExpr(NewMulOps);
- return true;
- }
+ if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor))
+ if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
+ if (!C->getAPInt().srem(FC->getAPInt())) {
+ SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
+ NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
+ S = SE.getMulExpr(NewMulOps);
+ return true;
+ }
}
// In an AddRec, check if both start and step are divisible.
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