[llvm] r213815 - SimplifyCFG: fix a bug in switch to table conversion
Manman
manman.ren at gmail.com
Thu Jul 24 08:16:22 PDT 2014
Sorry for the breakage. It seems simplifycfg (switch to table conversion) depends on the target.
I will update the testing case.
Thanks
Manman
> On Jul 24, 2014, at 5:56 AM, Tilmann Scheller <t.scheller at samsung.com> wrote:
>
> 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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