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[Transforms][SROA] Fixed assertion crash (PR30416)
AbandonedPublic

Authored by kbelochapka on Feb 20 2018, 7:33 PM.

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Details

Reviewers

• espindola
luqmana

Summary

Problem:
In certain situations during ALLOCA promotion, the promoteSingleBlockAlloca() function attempts to replace an instruction by the same instruction. This causes the assertion crash described in PR30416.

Solution:
Disable SROA for a Basic Block that can cause circular dependency.

Diff Detail

Event Timeline

kbelochapka created this revision.Feb 20 2018, 7:33 PM

Test?

In D43544#1014102, @lebedev.ri wrote:

Test?

Added test.

• espindola edited reviewers, added: • espindola; removed: • rafael.Mar 15 2018, 8:35 AM

luqmana resigned from this revision.Oct 6 2020, 12:14 AM

This problem was fixed:

commit 2cd9451d45d2cfd560395c25c12d27d8f6090d1b
Date:   Thu Jun 7 11:09:05 2018 +0000

[Mem2Reg] Avoid replacing load with itself in promoteSingleBlockAlloca.
We do the same thing in rewriteSingleStoreAlloca.

Differential Revision: https://reviews.llvm.org/D47825

@kbelochapka Abandon this patch?

Abandoned because of https://reviews.llvm.org/D47825

Revision Contents

Path

Size

lib/

Transforms/

Utils/

PromoteMemoryToRegister.cpp

3 lines

test/

Transforms/

SROA/

pr30416.ll

24 lines

Diff 135521

lib/Transforms/Utils/PromoteMemoryToRegister.cpp

Show First 20 Lines • Show All 503 Lines • ▼ Show 20 Lines	if (I == StoresByIndex.begin()) {
// Otherwise, there was a store before this load, the load takes its value.		// Otherwise, there was a store before this load, the load takes its value.
// Note, if the load was marked as nonnull we don't want to lose that		// Note, if the load was marked as nonnull we don't want to lose that
// information when we erase it. So we preserve it with an assume.		// information when we erase it. So we preserve it with an assume.
Value *ReplVal = std::prev(I)->second->getOperand(0);		Value *ReplVal = std::prev(I)->second->getOperand(0);
if (AC && LI->getMetadata(LLVMContext::MD_nonnull) &&		if (AC && LI->getMetadata(LLVMContext::MD_nonnull) &&
!isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))		!isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
addAssumeNonNull(AC, LI);		addAssumeNonNull(AC, LI);

		// we have a loop, bail out
		if (LI == ReplVal)
		return false;
LI->replaceAllUsesWith(ReplVal);		LI->replaceAllUsesWith(ReplVal);
}		}

LI->eraseFromParent();		LI->eraseFromParent();
LBI.deleteValue(LI);		LBI.deleteValue(LI);
}		}

// Remove the (now dead) stores and alloca.		// Remove the (now dead) stores and alloca.
▲ Show 20 Lines • Show All 480 Lines • Show Last 20 Lines

test/Transforms/SROA/pr30416.ll

				; RUN: opt < %s -sroa -S \| FileCheck %s
				target triple = "x86_64-pc-linux"

				; Make sure that SROA optimization is disabled on basic block
				; starting from label CF423.
				;CHECK-LABEL: CF423
				;CHECK-NEXT: store <4 x i64> %A4.0.load, <4 x i64>* undef, align 32
				;CHECK-NEXT: A4.0.load = load <4 x i64>, <4 x i64>* undef, align 32
				;CHECK-NEXT: store <4 x i64> zeroinitializer, <4 x i64>* undef, align 32
				;CHECK-NEXT: br label %CF423

				define void @autogen_SD998899922() {
				CF419:
				%A4 = alloca <4 x i64>, align 32
				br label %CF434
				CF434:
				br label %CF434
				CF423:
				store <4 x i64> %L38, <4 x i64>* %A4, align 32
				%L38 = load <4 x i64>, <4 x i64>* %A4, align 32
				store <4 x i64> zeroinitializer, <4 x i64>* %A4, align 32
				br label %CF423
				}