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Differential D66956

GlobalISel: Don't compute known bits for non-integral GEP
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Authored by arsenm on Aug 29 2019, 9:26 AM.

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aditya_nandakumar
aemerson
paquette

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arsenm created this revision.Aug 29 2019, 9:26 AM
Herald added subscribers: Petar.Avramovic, volkan, rovka, wdng. · View Herald TranscriptAug 29 2019, 9:26 AM
aditya_nandakumar accepted this revision.Aug 29 2019, 10:29 AM
This revision is now accepted and ready to land.Aug 29 2019, 10:29 AM
arsenm closed this revision.Aug 29 2019, 10:53 AM

r370392

Revision Contents

PathSize
lib/
CodeGen/
GlobalISel/
9 lines

Diff 217910

lib/CodeGen/GlobalISel/GISelKnownBits.cpp

Show First 20 Lines • Show All 144 Lines • ▼ Show 20 Lines case TargetOpcode::G_XOR: {
// Output known-0 bits are known if clear or set in both the LHS & RHS. // Output known-0 bits are known if clear or set in both the LHS & RHS.
APInt KnownZeroOut = (Known.Zero & Known2.Zero) | (Known.One & Known2.One); APInt KnownZeroOut = (Known.Zero & Known2.Zero) | (Known.One & Known2.One);
// Output known-1 are known to be set if set in only one of the LHS, RHS. // Output known-1 are known to be set if set in only one of the LHS, RHS.
Known.One = (Known.Zero & Known2.One) | (Known.One & Known2.Zero); Known.One = (Known.Zero & Known2.One) | (Known.One & Known2.Zero);
Known.Zero = KnownZeroOut; Known.Zero = KnownZeroOut;
break; break;
} }
case TargetOpcode::G_GEP: {
// G_GEP is like G_ADD. FIXME: Is this true for all targets? // G_GEP is like G_ADD. FIXME: Is this true for all targets?
case TargetOpcode::G_GEP: LLT Ty = MRI.getType(MI.getOperand(1).getReg());
if (DL.isNonIntegralAddressSpace(Ty.getAddressSpace()))
break;
LLVM_FALLTHROUGH;
}
case TargetOpcode::G_ADD: { case TargetOpcode::G_ADD: {
// Output known-0 bits are known if clear or set in both the low clear bits // Output known-0 bits are known if clear or set in both the low clear bits
// common to both LHS & RHS. For example, 8+(X<<3) is known to have the // common to both LHS & RHS. For example, 8+(X<<3) is known to have the
// low 3 bits clear. // low 3 bits clear.
// Output known-0 bits are also known if the top bits of each input are // Output known-0 bits are also known if the top bits of each input are
// known to be clear. For example, if one input has the top 10 bits clear // known to be clear. For example, if one input has the top 10 bits clear
// and the other has the top 8 bits clear, we know the top 7 bits of the // and the other has the top 8 bits clear, we know the top 7 bits of the
// output must be clear. // output must be clear.
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