[llvm] 3dc6e53 - [LoopPeel] Turn incorrect assert into a check
Fedor Sergeev via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 12 03:26:17 PDT 2020
Author: Max Kazantsev
Date: 2020-03-12T17:23:07+07:00
New Revision: 3dc6e53c9783cc2fe4e3eebd5fea9e3acd7bf900
URL: https://github.com/llvm/llvm-project/commit/3dc6e53c9783cc2fe4e3eebd5fea9e3acd7bf900
DIFF: https://github.com/llvm/llvm-project/commit/3dc6e53c9783cc2fe4e3eebd5fea9e3acd7bf900.diff
LOG: [LoopPeel] Turn incorrect assert into a check
Summary:
This patch replaces incorrectt assert with a check. Previously it asserts that
if SCEV cannot prove `isKnownPredicate(A != B)`, then it should be able to prove
`isKnownPredicate(A == B)`.
Both these fact may be not provable. It is shown in the provided test:
Could not prove: `{-294,+,-2}<%bb1> != 0`
Asserting: `{-294,+,-2}<%bb1> == 0`
Obviously, this SCEV is not equal to zero, but 0 is in its range so we cannot
also prove that it is not zero.
Instead of assert, we should be checking the required conditions explicitly.
Reviewers: lebedev.ri, fhahn, sanjoy, fedor.sergeev
Reviewed By: lebedev.ri
Subscribers: hiraditya, zzheng, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76050
Added:
llvm/test/Transforms/LoopUnroll/wrong_assert_in_peeling.ll
Modified:
llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
index afc4bbd7227d..43dfaf3e50dc 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -262,10 +262,9 @@ static unsigned countToEliminateCompares(Loop &L, unsigned MaxPeelCount,
// iteration. See if that makes !Pred become unknown again.
if (ICmpInst::isEquality(Pred) &&
!SE.isKnownPredicate(ICmpInst::getInversePredicate(Pred), NextIterVal,
- RightSCEV)) {
- assert(!SE.isKnownPredicate(Pred, IterVal, RightSCEV) &&
- SE.isKnownPredicate(Pred, NextIterVal, RightSCEV) &&
- "Expected Pred to go from known to unknown.");
+ RightSCEV) &&
+ !SE.isKnownPredicate(Pred, IterVal, RightSCEV) &&
+ SE.isKnownPredicate(Pred, NextIterVal, RightSCEV)) {
if (!CanPeelOneMoreIteration())
continue; // Need to peel one more iteration, but can't. Give up.
PeelOneMoreIteration(); // Great!
diff --git a/llvm/test/Transforms/LoopUnroll/wrong_assert_in_peeling.ll b/llvm/test/Transforms/LoopUnroll/wrong_assert_in_peeling.ll
new file mode 100644
index 000000000000..af0c6aeb7dbd
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/wrong_assert_in_peeling.ll
@@ -0,0 +1,110 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S < %s -loop-unroll | FileCheck %s
+; RUN: opt -S < %s -passes=unroll | FileCheck %s
+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"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label [[BB1:%.*]]
+; CHECK: bb1:
+; CHECK-NEXT: [[TMP:%.*]] = phi i32 [ -147, [[BB:%.*]] ], [ [[TMP14:%.*]], [[BB13:%.*]] ]
+; CHECK-NEXT: br label [[BB2_PEEL_BEGIN:%.*]]
+; CHECK: bb2.peel.begin:
+; CHECK-NEXT: br label [[BB2_PEEL:%.*]]
+; CHECK: bb2.peel:
+; CHECK-NEXT: [[TMP4_PEEL:%.*]] = add nsw i32 undef, [[TMP]]
+; CHECK-NEXT: br label [[BB5_PEEL:%.*]]
+; CHECK: bb5.peel:
+; CHECK-NEXT: [[TMP6_PEEL:%.*]] = icmp eq i32 undef, 33
+; CHECK-NEXT: br i1 [[TMP6_PEEL]], label [[BB7_PEEL:%.*]], label [[BB15_LOOPEXIT2:%.*]]
+; CHECK: bb7.peel:
+; CHECK-NEXT: [[TMP8_PEEL:%.*]] = sub nsw i32 undef, undef
+; CHECK-NEXT: [[TMP9_PEEL:%.*]] = icmp eq i32 [[TMP8_PEEL]], 0
+; CHECK-NEXT: br i1 [[TMP9_PEEL]], label [[BB10_PEEL:%.*]], label [[BB10_PEEL]]
+; CHECK: bb10.peel:
+; CHECK-NEXT: [[TMP11_PEEL:%.*]] = icmp eq i8 undef, 0
+; CHECK-NEXT: br i1 [[TMP11_PEEL]], label [[BB12_PEEL:%.*]], label [[BB17_LOOPEXIT3:%.*]]
+; CHECK: bb12.peel:
+; CHECK-NEXT: br i1 false, label [[BB13]], label [[BB2_PEEL_NEXT:%.*]]
+; CHECK: bb2.peel.next:
+; CHECK-NEXT: br label [[BB2_PEEL_NEXT1:%.*]]
+; CHECK: bb2.peel.next1:
+; CHECK-NEXT: br label [[BB1_PEEL_NEWPH:%.*]]
+; CHECK: bb1.peel.newph:
+; CHECK-NEXT: br label [[BB2:%.*]]
+; CHECK: bb2:
+; CHECK-NEXT: [[TMP3:%.*]] = phi i32 [ [[TMP4_PEEL]], [[BB1_PEEL_NEWPH]] ], [ [[TMP4:%.*]], [[BB12:%.*]] ]
+; CHECK-NEXT: [[TMP4]] = add nsw i32 [[TMP3]], [[TMP]]
+; CHECK-NEXT: br label [[BB5:%.*]]
+; CHECK: bb5:
+; CHECK-NEXT: br i1 false, label [[BB7:%.*]], label [[BB15_LOOPEXIT:%.*]]
+; CHECK: bb7:
+; CHECK-NEXT: br i1 undef, label [[BB10:%.*]], label [[BB10]]
+; CHECK: bb10:
+; CHECK-NEXT: br i1 false, label [[BB12]], label [[BB17_LOOPEXIT:%.*]]
+; CHECK: bb12:
+; CHECK-NEXT: br i1 false, label [[BB13_LOOPEXIT:%.*]], label [[BB2]], !llvm.loop !0
+; CHECK: bb13.loopexit:
+; CHECK-NEXT: br label [[BB13]]
+; CHECK: bb13:
+; CHECK-NEXT: [[TMP14]] = add nsw i32 [[TMP]], -1
+; CHECK-NEXT: br label [[BB1]]
+; CHECK: bb15.loopexit:
+; CHECK-NEXT: br label [[BB15:%.*]]
+; CHECK: bb15.loopexit2:
+; CHECK-NEXT: br label [[BB15]]
+; CHECK: bb15:
+; CHECK-NEXT: [[TMP16:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32(i32 17) [ "deopt"() ]
+; CHECK-NEXT: ret i32 [[TMP16]]
+; CHECK: bb17.loopexit:
+; CHECK-NEXT: br label [[BB17:%.*]]
+; CHECK: bb17.loopexit3:
+; CHECK-NEXT: br label [[BB17]]
+; CHECK: bb17:
+; CHECK-NEXT: [[TMP18:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32(i32 6) [ "deopt"() ]
+; CHECK-NEXT: ret i32 [[TMP18]]
+;
+bb:
+ br label %bb1
+
+bb1: ; preds = %bb13, %bb
+ %tmp = phi i32 [ -147, %bb ], [ %tmp14, %bb13 ]
+ br label %bb2
+
+bb2: ; preds = %bb12, %bb1
+ %tmp3 = phi i32 [ undef, %bb1 ], [ %tmp4, %bb12 ]
+ %tmp4 = add nsw i32 %tmp3, %tmp
+ br label %bb5
+
+bb5: ; preds = %bb2
+ %tmp6 = icmp eq i32 undef, 33
+ br i1 %tmp6, label %bb7, label %bb15
+
+bb7: ; preds = %bb5
+ %tmp8 = sub nsw i32 %tmp3, undef
+ %tmp9 = icmp eq i32 %tmp8, 0
+ br i1 %tmp9, label %bb10, label %bb10
+
+bb10: ; preds = %bb7, %bb7
+ %tmp11 = icmp eq i8 undef, 0
+ br i1 %tmp11, label %bb12, label %bb17
+
+bb12: ; preds = %bb10
+ br i1 false, label %bb13, label %bb2
+
+bb13: ; preds = %bb12
+ %tmp14 = add nsw i32 %tmp, -1
+ br label %bb1
+
+bb15: ; preds = %bb5
+ %tmp16 = call i32 (...) @llvm.experimental.deoptimize.i32(i32 17) [ "deopt"() ]
+ ret i32 %tmp16
+
+bb17: ; preds = %bb10
+ %tmp18 = call i32 (...) @llvm.experimental.deoptimize.i32(i32 6) [ "deopt"() ]
+ ret i32 %tmp18
+}
+
+declare i32 @llvm.experimental.deoptimize.i32(...)
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