[llvm] r197089 - Fix the PPC subsumes-predicate check

[Hal Finkel]

Bill,

Please pull this into the release branch.

Thanks again,
Hal

----- Original Message -----
> From: "Hal Finkel" <hfinkel at anl.gov>
> To: llvm-commits at cs.uiuc.edu
> Sent: Wednesday, December 11, 2013 5:12:26 PM
> Subject: [llvm] r197089 - Fix the PPC subsumes-predicate check
> 
> Author: hfinkel
> Date: Wed Dec 11 17:12:25 2013
> New Revision: 197089
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=197089&view=rev
> Log:
> Fix the PPC subsumes-predicate check
> 
> For one predicate to subsume another, they must both check the same
> condition
> register. Failure to check this prerequisite was causing miscompiles.
> 
> Fixes PR18003.
> 
> Added:
>     llvm/trunk/test/CodeGen/PowerPC/subsumes-pred-regs.ll
> Modified:
>     llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp
> 
> Modified: llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp?rev=197089&r1=197088&r2=197089&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp (original)
> +++ llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp Wed Dec 11
> 17:12:25 2013
> @@ -988,6 +988,10 @@ bool PPCInstrInfo::SubsumesPredicate(
>    if (Pred2[1].getReg() == PPC::CTR8 || Pred2[1].getReg() ==
>    PPC::CTR)
>      return false;
>  
> +  // P1 can only subsume P2 if they test the same condition
> register.
> +  if (Pred1[1].getReg() != Pred2[1].getReg())
> +    return false;
> +
>    PPC::Predicate P1 = (PPC::Predicate) Pred1[0].getImm();
>    PPC::Predicate P2 = (PPC::Predicate) Pred2[0].getImm();
>  
> 
> Added: llvm/trunk/test/CodeGen/PowerPC/subsumes-pred-regs.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/subsumes-pred-regs.ll?rev=197089&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/PowerPC/subsumes-pred-regs.ll (added)
> +++ llvm/trunk/test/CodeGen/PowerPC/subsumes-pred-regs.ll Wed Dec 11
> 17:12:25 2013
> @@ -0,0 +1,65 @@
> +; RUN: llc < %s -mcpu=ppc64 | FileCheck %s
> +target datalayout =
> "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
> +target triple = "powerpc64-unknown-linux-gnu"
> +
> +; Function Attrs: nounwind
> +define zeroext i1 @test1() unnamed_addr #0 align 2 {
> +
> +; CHECK-LABEL: @test1
> +
> +entry:
> +  br i1 undef, label %lor.end, label %lor.rhs
> +
> +lor.rhs:                                          ; preds = %entry
> +  unreachable
> +
> +lor.end:                                          ; preds = %entry
> +  br i1 undef, label %land.rhs, label %if.then
> +
> +if.then:                                          ; preds = %lor.end
> +  br i1 undef, label %return, label %if.end.i24
> +
> +if.end.i24:                                       ; preds = %if.then
> +  %0 = load i32* undef, align 4
> +  %lnot.i.i16.i23 = icmp eq i32 %0, 0
> +  br i1 %lnot.i.i16.i23, label %if.end7.i37, label %test.exit27.i34
> +
> +test.exit27.i34: ; preds = %if.end.i24
> +  br i1 undef, label %return, label %if.end7.i37
> +
> +if.end7.i37:                                      ; preds =
> %test.exit27.i34, %if.end.i24
> +  %tobool.i.i36 = icmp eq i8 undef, 0
> +  br i1 %tobool.i.i36, label %return, label %if.then9.i39
> +
> +if.then9.i39:                                     ; preds =
> %if.end7.i37
> +  br i1 %lnot.i.i16.i23, label %return, label %lor.rhs.i.i49
> +
> +; CHECK: .LBB0_7:
> +; CHECK:	beq 1, .LBB0_10
> +; CHECK:	beq 0, .LBB0_10
> +; CHECK: .LBB0_9:
> +
> +lor.rhs.i.i49:                                    ; preds =
> %if.then9.i39
> +  %cmp.i.i.i.i48 = icmp ne i64 undef, 0
> +  br label %return
> +
> +land.rhs:                                         ; preds = %lor.end
> +  br i1 undef, label %return, label %if.end.i
> +
> +if.end.i:                                         ; preds =
> %land.rhs
> +  br i1 undef, label %return, label %if.then9.i
> +
> +if.then9.i:                                       ; preds =
> %if.end.i
> +  br i1 undef, label %return, label %lor.rhs.i.i
> +
> +lor.rhs.i.i:                                      ; preds =
> %if.then9.i
> +  %cmp.i.i.i.i = icmp ne i64 undef, 0
> +  br label %return
> +
> +return:                                           ; preds =
> %lor.rhs.i.i, %if.then9.i, %if.end.i, %land.rhs, %lor.rhs.i.i49,
> %if.then9.i39, %if.end7.i37, %test.exit27.i34, %if.then
> +  %retval.0 = phi i1 [ false, %if.then ], [ false, %test.exit27.i34
> ], [ true, %if.end7.i37 ], [ true, %if.then9.i39 ], [
> %cmp.i.i.i.i48, %lor.rhs.i.i49 ], [ false, %land.rhs ], [ true,
> %if.end.i ], [ true, %if.then9.i ], [ %cmp.i.i.i.i, %lor.rhs.i.i ]
> +  ret i1 %retval.0
> +}
> +
> +attributes #0 = { nounwind }
> +
> 
> 
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-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory