[llvm] r213815 - SimplifyCFG: fix a bug in switch to table conversion
Tilmann Scheller
t.scheller at samsung.com
Thu Jul 24 05:56:01 PDT 2014
Hi Manman,
seems like this commit broke the clang-native-arm-cortex-a9 buildbot, can
you please have a look?
http://lab.llvm.org:8011/builders/clang-native-arm-cortex-a9/builds/20308
Regards,
Tilmann
-----Original Message-----
From: llvm-commits-bounces at cs.uiuc.edu
[mailto:llvm-commits-bounces at cs.uiuc.edu] On Behalf Of Manman Ren
Sent: Thursday, July 24, 2014 1:13 AM
To: llvm-commits at cs.uiuc.edu
Subject: [llvm] r213815 - SimplifyCFG: fix a bug in switch to table
conversion
Author: mren
Date: Wed Jul 23 18:13:23 2014
New Revision: 213815
URL: http://llvm.org/viewvc/llvm-project?rev=213815&view=rev
Log:
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
Added:
llvm/trunk/test/Transforms/SimplifyCFG/switch-table-bug.ll
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Simplify
CFG.cpp?rev=213815&r1=213814&r2=213815&view=diff
============================================================================
==
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Wed Jul 23 18:13:23
+++ 2014
@@ -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(Mod
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(Va
"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(SwitchIn
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(SwitchIn
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.
Added: llvm/trunk/test/Transforms/SimplifyCFG/switch-table-bug.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/s
witch-table-bug.ll?rev=213815&view=auto
============================================================================
==
--- llvm/trunk/test/Transforms/SimplifyCFG/switch-table-bug.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/switch-table-bug.ll Wed Jul
+++ 23 18:13:23 2014
@@ -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
+}
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