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Merging r213815:

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r213815 | mren | 2014-07-23 16:13:23 -0700 (Wed, 23 Jul 2014) | 17 lines

SimplifyCFG: fix a bug in switch to table conversion

We use gep to access the global array "switch.table", and the table index
should be treated as unsigned. When the highest bit is 1, this commit
zero-extends the index to an integer type with larger size.

For a switch on i2, we used to generate:
%switch.tableidx = sub i2 %0, -2
getelementptr inbounds [4 x i64]* @switch.table, i32 0, i2 %switch.tableidx

It is incorrect when %switch.tableidx is 2 or 3. The fix is to generate
%switch.tableidx = sub i2 %0, -2
%switch.tableidx.zext = zext i2 %switch.tableidx to i3
getelementptr inbounds [4 x i64]* @switch.table, i32 0, i3 %switch.tableidx.zext

rdar://17735071

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@214251 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg 2014-07-29 23:38:58 +00:00
parent 1b7ea62aa8
commit d97455ba30
2 changed files with 54 additions and 4 deletions
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17
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -3477,7 +3477,7 @@ namespace {
/// BuildLookup - Build instructions with Builder to retrieve the value at
/// the position given by Index in the lookup table.
Value *BuildLookup(Value *Index, IRBuilder<> &Builder);
Value *BuildLookup(Value *Index, uint64_t TableSize, IRBuilder<> &Builder);
/// WouldFitInRegister - Return true if a table with TableSize elements of
/// type ElementType would fit in a target-legal register.
@ -3598,7 +3598,8 @@ SwitchLookupTable::SwitchLookupTable(Module &M,
Kind = ArrayKind;
}
Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) {
Value *SwitchLookupTable::BuildLookup(Value *Index, uint64_t TableSize,
IRBuilder<> &Builder) {
switch (Kind) {
case SingleValueKind:
return SingleValue;
@ -3624,6 +3625,14 @@ Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) {
"switch.masked");
}
case ArrayKind: {
// Make sure the table index will not overflow when treated as signed.
if (IntegerType *IT = dyn_cast<IntegerType>(Index->getType()))
if (TableSize > (1 << (IT->getBitWidth() - 1)))
Index = Builder.CreateZExt(Index,
IntegerType::get(IT->getContext(),
IT->getBitWidth() + 1),
"switch.tableidx.zext");
Value *GEPIndices[] = { Builder.getInt32(0), Index };
Value *GEP = Builder.CreateInBoundsGEP(Array, GEPIndices,
"switch.gep");
@ -3823,7 +3832,7 @@ static bool SwitchToLookupTable(SwitchInst *SI,
SI->getDefaultDest()->removePredecessor(SI->getParent());
} else {
Value *Cmp = Builder.CreateICmpULT(TableIndex, ConstantInt::get(
MinCaseVal->getType(), TableSize));
MinCaseVal->getType(), TableSize));
Builder.CreateCondBr(Cmp, LookupBB, SI->getDefaultDest());
}
@ -3878,7 +3887,7 @@ static bool SwitchToLookupTable(SwitchInst *SI,
SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultLists[PHI],
DV, DL);
Value *Result = Table.BuildLookup(TableIndex, Builder);
Value *Result = Table.BuildLookup(TableIndex, TableSize, Builder);
// If the result is used to return immediately from the function, we want to
// do that right here.

41
test/Transforms/SimplifyCFG/switch-table-bug.ll Normal file
View File

@ -0,0 +1,41 @@
; RUN: opt -S -simplifycfg < %s | FileCheck %s
; rdar://17735071
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-darwin12.0.0"
; When tableindex can't fit into i2, we should extend the type to i3.
; CHECK-LABEL: @_TFO6reduce1E5toRawfS0_FT_Si
; CHECK: entry:
; CHECK-NEXT: sub i2 %0, -2
; CHECK-NEXT: zext i2 %switch.tableidx to i3
; CHECK-NEXT: getelementptr inbounds [4 x i64]* @switch.table, i32 0, i3 %switch.tableidx.zext
; CHECK-NEXT: load i64* %switch.gep
; CHECK-NEXT: ret i64 %switch.load
define i64 @_TFO6reduce1E5toRawfS0_FT_Si(i2) {
entry:
switch i2 %0, label %1 [
i2 0, label %2
i2 1, label %3
i2 -2, label %4
i2 -1, label %5
]
; <label>:1 ; preds = %entry
unreachable
; <label>:2 ; preds = %2
br label %6
; <label>:3 ; preds = %4
br label %6
; <label>:4 ; preds = %6
br label %6
; <label>:5 ; preds = %8
br label %6
; <label>:6 ; preds = %3, %5, %7, %9
%7 = phi i64 [ 3, %5 ], [ 2, %4 ], [ 1, %3 ], [ 0, %2 ]
ret i64 %7
}