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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.

llvm-svn: 197089
This commit is contained in:
Hal Finkel 2013-12-11 23:12:25 +00:00
parent 78f4d95d09
commit 94a6f380bb
2 changed files with 69 additions and 0 deletions
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4
llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
View File

@ -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();

65
llvm/test/CodeGen/PowerPC/subsumes-pred-regs.ll Normal file
View File

@ -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 }