2020-07-03 02:15:29 +08:00
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; RUN: opt -passes 'loop-reduce' -scalar-evolution-max-arith-depth=2 -S < %s | FileCheck %s
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[SCEV] Constant fold MultExpr before applying depth limit.
Summary:
Users of SCEV reasonably assume that multiplication of two constant
SCEVs will in turn be constant.
However, that is not always the case:
First, we can get here with reached depth limit, and will create
MultExpr SCEV `C1 * C2` and cache it.
Then, we can get here with the same operands, but with small depth
level. But this time we will find existing MultExpr SCEV and return
it, instead of expected constant SCEV.
This patch changes getMultExpr to not apply depth limit to all constant
operands expression, allowing them to be folded.
Reviewers: reames, mkazantsev
Subscribers: hiraditya, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D79893
2020-05-14 01:55:07 +08:00
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; RUN: opt -loop-reduce -scalar-evolution-max-arith-depth=2 -S < %s | FileCheck %s
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; This test should just compile cleanly without assertions.
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128-ni:1-p2:32:8:8:32-ni:2"
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define void @test(i32 %A, i32 %B, i32 %C) {
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; CHECK-LABEL: @test(
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; CHECK: inner_loop:
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; CHECK-NEXT: [[LSR_IV3:%.*]] = phi i32
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; CHECK-NEXT: [[LSR_IV1:%.*]] = phi i32
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; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32
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; CHECK: [[LSR_IV_NEXT:%.*]] = add i32 [[LSR_IV]], 3
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; CHECK-NEXT: [[LSR_IV_NEXT2:%.*]] = add i32 [[LSR_IV1]], 3
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; CHECK-NEXT: [[LSR_IV_NEXT4:%.*]] = add i32 [[LSR_IV3]], -3
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;
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entry:
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br label %outer_loop
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outer_loop:
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%phi2 = phi i32 [ %A, %entry ], [ 204, %outer_tail ]
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%phi3 = phi i32 [ %A, %entry ], [ 243, %outer_tail ]
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%phi4 = phi i32 [ %B, %entry ], [ %i35, %outer_tail ]
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br label %guard
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guard:
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%lcmp.mod = icmp eq i32 %C, 0
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br i1 %lcmp.mod, label %outer_tail, label %preheader
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preheader:
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%i15 = shl i32 %B, 1
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br label %inner_loop
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inner_loop:
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%phi5 = phi i32 [ %phi3, %preheader ], [ %i30, %inner_loop ]
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%phi6 = phi i32 [ %phi2, %preheader ], [ %i33, %inner_loop ]
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%iter = phi i32 [ %C, %preheader ], [ %iter.sub, %inner_loop ]
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%i17 = sub i32 %phi4, %phi6
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%i18 = sub i32 14, %phi5
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%i19 = mul i32 %i18, %C
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%factor.prol = shl i32 %phi5, 1
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%i20 = add i32 %i17, %factor.prol
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%i21 = add i32 %i20, %B
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%i22 = add i32 %i21, %i19
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%i23 = sub i32 14, %i22
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%i24 = mul i32 %i23, %C
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%factor.1.prol = shl i32 %i22, 1
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%i25 = add i32 %i17, %factor.1.prol
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%i27 = add i32 %i25, %i24
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%i29 = mul i32 %i25, %C
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%factor.2.prol = shl i32 %i27, 1
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%i30 = add i32 %i17, %factor.2.prol
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%i33 = add nsw i32 %phi6, -3
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%iter.sub = add i32 %iter, -1
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%iter.cmp = icmp eq i32 %iter.sub, 0
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br i1 %iter.cmp, label %outer_tail, label %inner_loop
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outer_tail:
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%phi7 = phi i32 [ %phi2, %guard ], [ %i33, %inner_loop ]
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%i35 = sub i32 %A, %phi7
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%cmp = icmp sgt i32 %i35, 9876
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br i1 %cmp, label %exit, label %outer_loop
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exit:
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ret void
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}
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