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[PowerPC] Use true offset value in "memrix" machine operands

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This is the second part of the change to always return "true"
offset values from getPreIndexedAddressParts, tackling the
case of "memrix" type operands.

This is about instructions like LD/STD that only have a 14-bit
field to encode immediate offsets, which are implicitly extended
by two zero bits by the machine, so that in effect we can access
16-bit offsets as long as they are a multiple of 4.

The PowerPC back end currently handles such instructions by
carrying the 14-bit value (as it will get encoded into the
actual machine instructions) in the machine operand fields
for such instructions.  This means that those values are
in fact not the true offset, but rather the offset divided
by 4 (and then truncated to an unsigned 14-bit value).

Like in the case fixed in r182012, this makes common code
operations on such offset values not work as expected.
Furthermore, there doesn't really appear to be any strong
reason why we should encode machine operands this way.

This patch therefore changes the encoding of "memrix" type
machine operands to simply contain the "true" offset value
as a signed immediate value, while enforcing the rules that
it must fit in a 16-bit signed value and must also be a
multiple of 4.

This change must be made simultaneously in all places that
access machine operands of this type.  However, just about
all those changes make the code simpler; in many cases we
can now just share the same code for memri and memrix
operands.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182032 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ulrich Weigand
2013-05-16 17:58:02 +00:00
parent 2a5e8c328e
commit 347a5079e1
12 changed files with 61 additions and 194 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
View File

@@ -137,14 +137,6 @@ void PPCInstPrinter::printU16ImmOperand(const MCInst *MI, unsigned OpNo,
O << (unsigned short)MI->getOperand(OpNo).getImm();
}
void PPCInstPrinter::printS16X4ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (MI->getOperand(OpNo).isImm())
O << (short)(MI->getOperand(OpNo).getImm()*4);
else
printOperand(MI, OpNo, O);
}
void PPCInstPrinter::printBranchOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (!MI->getOperand(OpNo).isImm())
@@ -191,22 +183,6 @@ void PPCInstPrinter::printMemRegImm(const MCInst *MI, unsigned OpNo,
O << ')';
}
void PPCInstPrinter::printMemRegImmShifted(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (MI->getOperand(OpNo).isImm())
printS16X4ImmOperand(MI, OpNo, O);
else
printSymbolLo(MI, OpNo, O);
O << '(';
if (MI->getOperand(OpNo+1).getReg() == PPC::R0)
O << "0";
else
printOperand(MI, OpNo+1, O);
O << ')';
}
void PPCInstPrinter::printMemRegReg(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
// When used as the base register, r0 reads constant zero rather than

2
lib/Target/PowerPC/InstPrinter/PPCInstPrinter.h
View File

@@ -50,14 +50,12 @@ public:
void printU6ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printS16ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printU16ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printS16X4ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printBranchOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printAbsAddrOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printcrbitm(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printMemRegImm(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printMemRegImmShifted(const MCInst *MI, unsigned OpNo, raw_ostream &O);
void printMemRegReg(const MCInst *MI, unsigned OpNo, raw_ostream &O);
// FIXME: Remove