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Fix bug 25440: GVN assertion after coercing loads

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Optimizations like LoadPRE in GVN will insert new instructions.
If the insertion point is in a already processed BB, they should
get a value number explicitly. If the insertion point is after
current instruction, then just leave it. However, current GVN framework
has no support for it.
In this patch, we just bail out if a VN can't be found.

Dfferential Revision: http://reviews.llvm.org/D14670

A    test/Transforms/GVN/pr25440.ll
M    lib/Transforms/Scalar/GVN.cpp


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253536 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Weiming Zhao 2015-11-19 02:45:18 +00:00
parent 697477e00c
commit f9d8b8d2ab
2 changed files with 120 additions and 1 deletions
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13
lib/Transforms/Scalar/GVN.cpp
View File

@ -129,6 +129,7 @@ namespace {
uint32_t lookup(Value *V) const;
uint32_t lookup_or_add_cmp(unsigned Opcode, CmpInst::Predicate Pred,
Value *LHS, Value *RHS);
bool exists(Value *V) const;
void add(Value *V, uint32_t num);
void clear();
void erase(Value *v);
@ -389,6 +390,9 @@ uint32_t ValueTable::lookup_or_add_call(CallInst *C) {
}
}
/// Returns true if a value number exists for the specified value.
bool ValueTable::exists(Value *V) const { return valueNumbering.count(V) != 0; }
/// lookup_or_add - Returns the value number for the specified value, assigning
/// it a new number if it did not have one before.
uint32_t ValueTable::lookup_or_add(Value *V) {
@ -2534,7 +2538,14 @@ bool GVN::performScalarPREInsertion(Instruction *Instr, BasicBlock *Pred,
Value *Op = Instr->getOperand(i);
if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
continue;
// This could be a newly inserted instruction, in which case, we won't
// find a value number, and should give up before we hurt ourselves.
// FIXME: Rewrite the infrastructure to let it easier to value number
// and process newly inserted instructions.
if (!VN.exists(Op)) {
success = false;
break;
}
if (Value *V = findLeader(Pred, VN.lookup(Op))) {
Instr->setOperand(i, V);
} else {

108
test/Transforms/GVN/pr25440.ll Normal file
View File

@ -0,0 +1,108 @@
;RUN: opt -gvn -S < %s | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n8:16:32-S64"
target triple = "thumbv7--linux-gnueabi"
%struct.a = type { i16, i16, [1 x %union.a] }
%union.a = type { i32 }
@length = external global [0 x i32], align 4
; Function Attrs: nounwind
define fastcc void @foo(%struct.a* nocapture readonly %x) {
;CHECK-LABEL: foo
entry:
br label %bb0
bb0: ; preds = %land.lhs.true, %entry
;CHECK: bb0:
%x.tr = phi %struct.a* [ %x, %entry ], [ null, %land.lhs.true ]
%code1 = getelementptr inbounds %struct.a, %struct.a* %x.tr, i32 0, i32 0
%0 = load i16, i16* %code1, align 4
; CHECK: load i32, i32*
%conv = zext i16 %0 to i32
switch i32 %conv, label %if.end.50 [
i32 43, label %cleanup
i32 52, label %if.then.5
]
if.then.5: ; preds = %bb0
br i1 undef, label %land.lhs.true, label %if.then.26
land.lhs.true: ; preds = %if.then.5
br i1 undef, label %cleanup, label %bb0
if.then.26: ; preds = %if.then.5
%x.tr.lcssa163 = phi %struct.a* [ %x.tr, %if.then.5 ]
br i1 undef, label %cond.end, label %cond.false
cond.false: ; preds = %if.then.26
; CHECK: cond.false:
; CHECK-NOT: load
%mode = getelementptr inbounds %struct.a, %struct.a* %x.tr.lcssa163, i32 0, i32 1
%bf.load = load i16, i16* %mode, align 2
%bf.shl = shl i16 %bf.load, 8
br label %cond.end
cond.end: ; preds = %cond.false, %if.then.26
br i1 undef, label %if.then.44, label %cleanup
if.then.44: ; preds = %cond.end
unreachable
if.end.50: ; preds = %bb0
;%CHECK: if.end.50:
%conv.lcssa = phi i32 [ %conv, %bb0 ]
%arrayidx52 = getelementptr inbounds [0 x i32], [0 x i32]* @length, i32 0, i32 %conv.lcssa
%1 = load i32, i32* %arrayidx52, align 4
br i1 undef, label %for.body.57, label %cleanup
for.body.57: ; preds = %if.end.50
%i.2157 = add nsw i32 %1, -1
unreachable
cleanup: ; preds = %if.end.50, %cond.end, %land.lhs.true, %bb0
ret void
}
@yy_c_buf_p = external unnamed_addr global i8*, align 4
@dfg_text = external global i8*, align 4
define void @dfg_lex() {
;CHECK-LABEL: dfg_lex
entry:
br label %while.bodythread-pre-split
while.bodythread-pre-split: ; preds = %while.end, %while.end, %entry
br i1 undef, label %if.then.14, label %if.end.15
if.then.14: ; preds = %while.end, %while.bodythread-pre-split
%v1 = load i32, i32* bitcast (i8** @dfg_text to i32*), align 4
%sub.ptr.sub = sub i32 undef, %v1
br label %if.end.15
if.end.15: ; preds = %if.then.14, %while.bodythread-pre-split
%v2 = load i8*, i8** @yy_c_buf_p, align 4
br label %while.cond.16
while.cond.16: ; preds = %while.cond.16, %if.end.15
br i1 undef, label %while.cond.16, label %while.end
while.end: ; preds = %while.cond.16
%add.ptr = getelementptr inbounds i8, i8* %v2, i32 undef
store i8* %add.ptr, i8** @dfg_text, align 4
%sub.ptr.rhs.cast25 = ptrtoint i8* %add.ptr to i32
%sub.ptr.sub26 = sub i32 0, %sub.ptr.rhs.cast25
switch i32 undef, label %sw.default [
i32 65, label %while.bodythread-pre-split
i32 3, label %return
i32 57, label %while.bodythread-pre-split
i32 60, label %if.then.14
]
sw.default: ; preds = %while.end
unreachable
return: ; preds = %while.end
ret void
}