http://llvm.org/bugs/show_bug.cgi?id=8317
Summary: X86InstrInfo::convertToThreeAddress violates register
class constraints
Product: libraries
Version: trunk
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
X86InstrInfo::convertToThreeAddress can change an SHL instruction into an LEA.
This can break register class constraints because LEA cannot take ESP as an
offset while SHL can.
LEA requires a GR32_NOSP register while SHL only requires a GR32.
This is an academic exercise since ESP is always reserved anyway, so it doesn't
cause any invalid code to be generated.
It does break the machine code verifier, though.
X86InstrInfo::convertToThreeAddress should switch the regclass of SrcReg from
GR32 to GR32_NOSP, and we may want to use GR32_NOSP as the default class for
i32 values.
The same applies to GR64_NOSP.
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