[llvm] r249187 - [WebAssembly] Fix CFG stackification of nested loops.

[Dan Gohman via llvm-commits]

Hi Richard,

Thanks for reporting it. It's now fixed in r249217.

Dan

On Fri, Oct 2, 2015 at 4:46 PM, Richard Trieu <rtrieu at google.com> wrote:

> Hi Dan,
>
> I am getting the follow testing failure when running the test
> cfg-stackify.ll:
>
> cfg-stackify.ll:203:10: error: expected string not found in input
> ; CHECK: (loop $BB8_1)
>          ^
> <stdin>:177:2: note: scanning from here
>  (loop $BB8_2)
>  ^
>
> Diff the output from llc run line between revisions:
> 11c11
> < (loop $BB0_3)
> ---
> > (loop $BB0_2)
> 32c32
> < (loop $BB1_3)
> ---
> > (loop $BB1_2)
> 55c55
> < (loop $BB2_2)
> ---
> > (loop $BB2_1)
> 162c162
> < (loop $BB7_2)
> ---
> > (loop $BB7_1)
> 177c177
> < (loop $BB8_2)
> ---
> > (loop $BB8_1)
> 239,263d238
> <
> < ;; .globl test3
> < (func $test3
> <  (param i32)
> < (block $BB11_1)
> < (setlocal @0 (argument 0))
> < (setlocal @1 (immediate 0))
> < (brif $BB11_1 @1)
> < (br $BB11_2)
> < BB11_1:
> < (return)
> < BB11_2:
> < (loop $BB11_5)
> < (block $BB11_4)
> < (block $BB11_2)
> < (setlocal @3 (eq @4 @1))
> < BB11_3:
> < (loop $BB11_4)
> < (setlocal @5 (eq @6 @0))
> < (brif $BB11_4 @5)
> < (br $BB11_3)
> < BB11_4:
> < (call $bar)
> < (br $BB11_2)
> < ) ;; end func $test3
>
>
> On Fri, Oct 2, 2015 at 2:11 PM, Dan Gohman via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: djg
>> Date: Fri Oct  2 16:11:36 2015
>> New Revision: 249187
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=249187&view=rev
>> Log:
>> [WebAssembly] Fix CFG stackification of nested loops.
>>
>> Modified:
>>     llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
>>     llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify.ll
>>
>> Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp?rev=249187&r1=249186&r2=249187&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
>> (original)
>> +++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp Fri Oct
>> 2 16:11:36 2015
>> @@ -194,8 +194,10 @@ static void SortBlocks(MachineFunction &
>>      if (MachineLoop *Loop = MLI.getLoopFor(&MBB)) {
>>        // Assert that loops are contiguous.
>>        assert(Loop->getHeader() == Loop->getTopBlock());
>> -      assert(Loop->getHeader() == &MBB ||
>> -             MLI.getLoopFor(prev(MachineFunction::iterator(&MBB))) ==
>> Loop);
>> +      assert((Loop->getHeader() == &MBB ||
>> +              Loop->contains(
>> +
>> MLI.getLoopFor(prev(MachineFunction::iterator(&MBB))))) &&
>> +             "Loop isn't contiguous");
>>      } else {
>>        // Assert that non-loops have no backedge predecessors.
>>        for (auto Pred : MBB.predecessors())
>> @@ -245,9 +247,18 @@ static void PlaceMarkers(MachineFunction
>>    for (auto &MBB : MF) {
>>      // Place the LOOP for loops.
>>      if (MachineLoop *Loop = MLI.getLoopFor(&MBB))
>> -      if (Loop->getHeader() == &MBB)
>> +      if (Loop->getHeader() == &MBB) {
>> +        // The operand of a LOOP is the first block after the loop. If
>> the loop
>> +        // is the bottom of the function, insert a dummy block at the
>> end.
>> +        MachineBasicBlock *Bottom = Loop->getBottomBlock();
>> +        auto Iter = next(MachineFunction::iterator(Bottom));
>> +        if (Iter == MF.end()) {
>> +          MF.push_back(MF.CreateMachineBasicBlock());
>> +          Iter = next(MachineFunction::iterator(Bottom));
>> +        }
>>          BuildMI(MBB, MBB.begin(), DebugLoc(), TII.get(WebAssembly::LOOP))
>> -            .addMBB(Loop->getBottomBlock());
>> +            .addMBB(Iter);
>> +      }
>>
>>      // Check for forward branches and switches that need BLOCKS placed.
>>      for (auto &Term : MBB.terminators())
>>
>> Modified: llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify.ll?rev=249187&r1=249186&r2=249187&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify.ll (original)
>> +++ llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify.ll Fri Oct  2
>> 16:11:36 2015
>> @@ -272,3 +272,33 @@ exit:
>>    store volatile i32 4, i32* %p
>>    ret i32 0
>>  }
>> +
>> +; Test that nested loops are handled.
>> +
>> +declare void @bar()
>> +
>> +define void @test3(i32 %w)  {
>> +entry:
>> +  br i1 undef, label %outer.ph, label %exit
>> +
>> +outer.ph:
>> +  br label %outer
>> +
>> +outer:
>> +  %tobool = icmp eq i32 undef, 0
>> +  br i1 %tobool, label %inner, label %unreachable
>> +
>> +unreachable:
>> +  unreachable
>> +
>> +inner:
>> +  %c = icmp eq i32 undef, %w
>> +  br i1 %c, label %if.end, label %inner
>> +
>> +exit:
>> +  ret void
>> +
>> +if.end:
>> +  call void @bar()
>> +  br label %outer
>> +}
>>
>>
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>>
>
>
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