[llvm] r247356 - [InstCombineCalls] Use isKnownNonNullAt() to check nullness of passing arguments at callsite

[Sanjoy Das via llvm-commits]

Yeah, I think this is marking non pointer arguments as nonnull.

This was probably an existing issue that did not happen in practice
because `isKnownNonNull` does not return true for non pointer values.
`isKnownNonNullAt` is smarter and will return true for a provably
non-zero integer.

-- Sanjoy

On Thu, Sep 10, 2015 at 6:38 PM, Mehdi Amini via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Hi,
>
> I reverted in r247371 because it broke llvm/test/Transforms/InstCombine/pr8547.ll:
>
> --
> Exit Code: 2
>
> Command Output (stderr):
> --
> Wrong types for attribute: byval inalloca nest noalias nocapture nonnull readnone readonly sret dereferenceable(1) dereferenceable_or_null(1)
>   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str, i64 0, i64 0), i32 nonnull %conv2) #0
> LLVM ERROR: Broken function found, compilation aborted!
> FileCheck error: '-' is empty.
>
> --
>
> See for instance: http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/28054/steps/test_llvm/logs/stdio
>
> Best,
>
> —
> Mehdi
>
>> On Sep 10, 2015, at 4:04 PM, Chen Li via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: chenli
>> Date: Thu Sep 10 18:04:49 2015
>> New Revision: 247356
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=247356&view=rev
>> Log:
>> [InstCombineCalls] Use isKnownNonNullAt() to check nullness of passing arguments at callsite
>>
>> Summary: This patch replaces isKnownNonNull() with isKnownNonNullAt() when checking nullness of passing arguments at callsite. In this way it can handle cases where the argument does not have nonnull attribute but has a dominating null check from the CFG.
>>
>> Reviewers: reames
>>
>> Subscribers: llvm-commits
>>
>> Differential Revision: http://reviews.llvm.org/D12779
>>
>> Added:
>>    llvm/trunk/test/Transforms/InstCombine/call_nonnull_arg.ll
>> Modified:
>>    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=247356&r1=247355&r2=247356&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Thu Sep 10 18:04:49 2015
>> @@ -1537,7 +1537,7 @@ Instruction *InstCombiner::visitCallSite
>>   unsigned ArgNo = 0;
>>   for (Value *V : CS.args()) {
>>     if (!CS.paramHasAttr(ArgNo+1, Attribute::NonNull) &&
>> -        isKnownNonNull(V)) {
>> +        isKnownNonNullAt(V, CS.getInstruction(), DT, TLI)) {
>>       AttributeSet AS = CS.getAttributes();
>>       AS = AS.addAttribute(CS.getInstruction()->getContext(), ArgNo+1,
>>                            Attribute::NonNull);
>>
>> Added: llvm/trunk/test/Transforms/InstCombine/call_nonnull_arg.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/call_nonnull_arg.ll?rev=247356&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/InstCombine/call_nonnull_arg.ll (added)
>> +++ llvm/trunk/test/Transforms/InstCombine/call_nonnull_arg.ll Thu Sep 10 18:04:49 2015
>> @@ -0,0 +1,17 @@
>> +; RUN: opt < %s -instcombine -S | FileCheck %s
>> +
>> +; InstCombine should mark null-checked argument as nonnull at callsite
>> +declare void @dummy(i32*)
>> +
>> +define void @test(i32* %a) {
>> +; CHECK-LABEL: @test
>> +; CHECK: call void @dummy(i32* nonnull %a)
>> +entry:
>> +  %cond = icmp eq i32* %a, null
>> +  br i1 %cond, label %is_null, label %not_null
>> +not_null:
>> +  call void @dummy(i32* %a)
>> +  ret void
>> +is_null:
>> +  unreachable
>> +}
>>
>>
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-- 
Sanjoy Das
http://playingwithpointers.com