[llvm-commits] [llvm] r164866 - in /llvm/trunk: lib/Transforms/Scalar/CodeGenPrepare.cpp test/CodeGen/X86/2012-09-28-CGPBug.ll

[Evan Cheng]

In global JT, he addresses of other blocks are used. If they are merged into other blocks, then you end up with invalid values like this:
_JT:
        .long   Ltmp2-Ltmp0
        .long   Ltmp1-Ltmp0
        .long   1-Ltmp2  
        .long   1-Ltmp1

Evan

On Oct 5, 2012, at 1:05 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

> Sorry, what was the problem? The indirectbr in the testcase can only
> jump to label %17 and label %18, so it should be fine to remove the
> other basic blocks.
> 
> On 28 September 2012 19:58, Evan Cheng <evan.cheng at apple.com> wrote:
>> Author: evancheng
>> Date: Fri Sep 28 18:58:57 2012
>> New Revision: 164866
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=164866&view=rev
>> Log:
>> Do not delete BBs if their addresses are taken. rdar://12396696
>> 
>> Added:
>>    llvm/trunk/test/CodeGen/X86/2012-09-28-CGPBug.ll
>> Modified:
>>    llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp
>> 
>> Modified: llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp?rev=164866&r1=164865&r2=164866&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp Fri Sep 28 18:58:57 2012
>> @@ -226,7 +226,8 @@
>>     // edge, just collapse it.
>>     BasicBlock *SinglePred = BB->getSinglePredecessor();
>> 
>> -    if (!SinglePred || SinglePred == BB) continue;
>> +    // Don't merge if BB's address is taken.
>> +    if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
>> 
>>     BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
>>     if (Term && !Term->isConditional()) {
>> @@ -788,7 +789,7 @@
>>   }
>> 
>>   // If we eliminated all predecessors of the block, delete the block now.
>> -  if (Changed && pred_begin(BB) == pred_end(BB))
>> +  if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
>>     BB->eraseFromParent();
>> 
>>   return Changed;
>> 
>> Added: llvm/trunk/test/CodeGen/X86/2012-09-28-CGPBug.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2012-09-28-CGPBug.ll?rev=164866&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/2012-09-28-CGPBug.ll (added)
>> +++ llvm/trunk/test/CodeGen/X86/2012-09-28-CGPBug.ll Fri Sep 28 18:58:57 2012
>> @@ -0,0 +1,53 @@
>> +; RUN: llc -mtriple=i386-apple-macosx < %s | FileCheck %s
>> +; rdar://12396696
>> +
>> + at JT = global [4 x i32] [i32 sub (i32 ptrtoint (i8* blockaddress(@h, %18) to i32), i32 ptrtoint (i8* blockaddress(@h, %11) to i32)), i32 sub (i32 ptrtoint (i8* blockaddress(@h, %17) to i32), i32 ptrtoint (i8* blockaddress(@h, %11) to i32)), i32 sub (i32 ptrtoint (i8* blockaddress(@h, %22) to i32), i32 ptrtoint (i8* blockaddress(@h, %18) to i32)), i32 sub (i32 ptrtoint (i8* blockaddress(@h, %22) to i32), i32 ptrtoint (i8* blockaddress(@h, %17) to i32))]
>> + at gGlobalLock = external global i8*
>> + at .str40 = external global [35 x i8]
>> +
>> +; CHECK: _JT:
>> +; CHECK-NOT: .long Ltmp{{[0-9]+}}-1
>> +; CHECK-NOT: .long 1-Ltmp{{[0-9]+}}
>> +; CHECK: .long Ltmp{{[0-9]+}}-Ltmp{{[0-9]+}}
>> +; CHECK: .long Ltmp{{[0-9]+}}-Ltmp{{[0-9]+}}
>> +; CHECK: .long Ltmp{{[0-9]+}}-Ltmp{{[0-9]+}}
>> +; CHECK: .long Ltmp{{[0-9]+}}-Ltmp{{[0-9]+}}
>> +
>> +define void @h(i8*) nounwind ssp {
>> +  %2 = alloca i8*
>> +  store i8* %0, i8** %2
>> +  %3 = load i8** %2
>> +  %4 = bitcast i8* %3 to { i32, i32 }*
>> +  %5 = getelementptr { i32, i32 }* %4, i32 0, i32 0
>> +  %6 = load i32* %5
>> +  %7 = srem i32 %6, 2
>> +  %8 = icmp slt i32 %6, 2
>> +  %9 = select i1 %8, i32 %6, i32 %7
>> +  %10 = icmp eq i32 %9, 0
>> +  br label %11
>> +
>> +; <label>:11                                      ; preds = %1
>> +  %12 = zext i1 %10 to i32
>> +  %13 = getelementptr [4 x i32]* @JT, i32 0, i32 %12
>> +  %14 = load i32* %13
>> +  %15 = add i32 %14, ptrtoint (i8* blockaddress(@h, %11) to i32)
>> +  %16 = inttoptr i32 %15 to i8*
>> +  indirectbr i8* %16, [label %17, label %18]
>> +
>> +; <label>:17                                      ; preds = %11
>> +  tail call void (i8*, ...)* @g(i8* getelementptr inbounds ([35 x i8]* @.str40, i32 0, i32 0))
>> +  br label %22
>> +
>> +; <label>:18                                      ; preds = %11
>> +  %19 = call i32 @f(i32 -1037694186) nounwind
>> +  %20 = inttoptr i32 %19 to i32 (i8**)*
>> +  %21 = tail call i32 %20(i8** @gGlobalLock)
>> +  br label %22
>> +
>> +; <label>:22                                      ; preds = %18, %17
>> +  ret void
>> +}
>> +
>> +declare i32 @f(i32)
>> +
>> +declare void @g(i8*, ...)
>> 
>> 
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