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fix: SLPVectorizer crashes for unreachable blocks containing not schedulable instructions.

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In unreachable blocks it's legal to have instructions like "%x = op %x".
Such instuctions are not schedulable. Therefore the SLPVectorizer has to check for
unreachable blocks and ignore them.

Fixes bug 20646.

llvm-svn: 216256
This commit is contained in:
Erik Eckstein 2014-08-22 01:18:39 +00:00
parent 206040e6b5
commit ac5cb54255
2 changed files with 48 additions and 0 deletions
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8
lib/Transforms/Vectorize/SLPVectorizer.cpp
View File

@ -976,6 +976,14 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth) {
Instruction *VL0 = cast<Instruction>(VL[0]); Instruction *VL0 = cast<Instruction>(VL[0]);
BasicBlock *BB = cast<Instruction>(VL0)->getParent(); BasicBlock *BB = cast<Instruction>(VL0)->getParent();
if (!DT->isReachableFromEntry(BB)) {
// Don't go into unreachable blocks. They may contain instructions with
// dependency cycles which confuse the final scheduling.
DEBUG(dbgs() << "SLP: bundle in unreachable block.\n");
newTreeEntry(VL, false);
return;
}
// Check that every instructions appears once in this bundle. // Check that every instructions appears once in this bundle.
for (unsigned i = 0, e = VL.size(); i < e; ++i) for (unsigned i = 0, e = VL.size(); i < e; ++i)
for (unsigned j = i+1; j < e; ++j) for (unsigned j = i+1; j < e; ++j)

40
test/Transforms/SLPVectorizer/X86/unreachable.ll Normal file
View File

@ -0,0 +1,40 @@
; RUN: opt < %s -basicaa -slp-vectorizer -S -mtriple=x86_64-apple-macosx10.8.0 -mcpu=corei7
; Check if the SLPVectorizer does not crash when handling
; unreachable blocks with unscheduleable instructions.
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.9.0"
define void @foo(i32* nocapture %x) #0 {
entry:
br label %bb2
bb1: ; an unreachable block
%t3 = getelementptr inbounds i32* %x, i64 4
%t4 = load i32* %t3, align 4
%t5 = getelementptr inbounds i32* %x, i64 5
%t6 = load i32* %t5, align 4
%bad = fadd float %bad, 0.000000e+00 ; <- an instruction with self dependency,
; but legal in unreachable code
%t7 = getelementptr inbounds i32* %x, i64 6
%t8 = load i32* %t7, align 4
%t9 = getelementptr inbounds i32* %x, i64 7
%t10 = load i32* %t9, align 4
br label %bb2
bb2:
%t1.0 = phi i32 [ %t4, %bb1 ], [ 2, %entry ]
%t2.0 = phi i32 [ %t6, %bb1 ], [ 2, %entry ]
%t3.0 = phi i32 [ %t8, %bb1 ], [ 2, %entry ]
%t4.0 = phi i32 [ %t10, %bb1 ], [ 2, %entry ]
store i32 %t1.0, i32* %x, align 4
%t12 = getelementptr inbounds i32* %x, i64 1
store i32 %t2.0, i32* %t12, align 4
%t13 = getelementptr inbounds i32* %x, i64 2
store i32 %t3.0, i32* %t13, align 4
%t14 = getelementptr inbounds i32* %x, i64 3
store i32 %t4.0, i32* %t14, align 4
ret void
}