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[mips] Do not include offset into %got expression for global symbols

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Now pseudo instruction `la $6, symbol+8($6)` is expanding into the following
chain of commands:
```
lw    $1, %got(symbol+8)($gp)
addiu $1, $1, 8
addu  $6, $1, $6
```

This is incorrect. When a linker handles the `R_MIPS_GOT16` relocation,
it does not expect to get any addend and breaks on assertion. Otherwise
it has to create new GOT entry for each unique "sym + offset" pair.
Offset for a global symbol should be added to result of loading GOT
entry by a separate `add` command.

The patch fixes the problem by stripping off an offset from the expression
passed to the `%got`. That's interesting that even current code inserts
a separate `add` command.

Differential Revision: https://reviews.llvm.org/D66552

llvm-svn: 369755
This commit is contained in:
Simon Atanasyan 2019-08-23 13:36:14 +00:00
parent 29a5b2fd9c
commit 493b163f5d
3 changed files with 38 additions and 30 deletions
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32
lib/Target/Mips/AsmParser/MipsAsmParser.cpp
View File

@ -2884,16 +2884,18 @@ bool MipsAsmParser::loadAndAddSymbolAddress(const MCExpr *SymExpr,
return true;
}
bool IsLocalSym =
Res.getSymA()->getSymbol().isInSection() ||
Res.getSymA()->getSymbol().isTemporary() ||
(Res.getSymA()->getSymbol().isELF() &&
cast<MCSymbolELF>(Res.getSymA()->getSymbol()).getBinding() ==
ELF::STB_LOCAL);
// The case where the result register is $25 is somewhat special. If the
// symbol in the final relocation is external and not modified with a
// constant then we must use R_MIPS_CALL16 instead of R_MIPS_GOT16.
if ((DstReg == Mips::T9 || DstReg == Mips::T9_64) && !UseSrcReg &&
Res.getConstant() == 0 &&
!(Res.getSymA()->getSymbol().isInSection() ||
Res.getSymA()->getSymbol().isTemporary() ||
(Res.getSymA()->getSymbol().isELF() &&
cast<MCSymbolELF>(Res.getSymA()->getSymbol()).getBinding() ==
ELF::STB_LOCAL))) {
Res.getConstant() == 0 && !IsLocalSym) {
const MCExpr *CallExpr =
MipsMCExpr::create(MipsMCExpr::MEK_GOT_CALL, SymExpr, getContext());
TOut.emitRRX(Mips::LW, DstReg, GPReg, MCOperand::createExpr(CallExpr),
@ -2902,8 +2904,8 @@ bool MipsAsmParser::loadAndAddSymbolAddress(const MCExpr *SymExpr,
}
// The remaining cases are:
// External GOT: lw $tmp, %got(symbol+offset)($gp)
// >addiu $tmp, $tmp, %lo(offset)
// External GOT: lw $tmp, %got(symbol)($gp)
// >addiu $tmp, $tmp, offset
// >addiu $rd, $tmp, $rs
// Local GOT: lw $tmp, %got(symbol+offset)($gp)
// addiu $tmp, $tmp, %lo(symbol+offset)($gp)
@ -2911,17 +2913,19 @@ bool MipsAsmParser::loadAndAddSymbolAddress(const MCExpr *SymExpr,
// The addiu's marked with a '>' may be omitted if they are redundant. If
// this happens then the last instruction must use $rd as the result
// register.
const MipsMCExpr *GotExpr =
MipsMCExpr::create(MipsMCExpr::MEK_GOT, SymExpr, getContext());
const MipsMCExpr *GotExpr = nullptr;
const MCExpr *LoExpr = nullptr;
if (Res.getSymA()->getSymbol().isInSection() ||
Res.getSymA()->getSymbol().isTemporary())
if (IsLocalSym) {
GotExpr = MipsMCExpr::create(MipsMCExpr::MEK_GOT, SymExpr, getContext());
LoExpr = MipsMCExpr::create(MipsMCExpr::MEK_LO, SymExpr, getContext());
else if (Res.getConstant() != 0) {
} else {
// External symbols fully resolve the symbol with just the %got(symbol)
// but we must still account for any offset to the symbol for expressions
// like symbol+8.
LoExpr = MCConstantExpr::create(Res.getConstant(), getContext());
GotExpr =
MipsMCExpr::create(MipsMCExpr::MEK_GOT, Res.getSymA(), getContext());
if (Res.getConstant() != 0)
LoExpr = MCConstantExpr::create(Res.getConstant(), getContext());
}
unsigned TmpReg = DstReg;

28
test/MC/Mips/macro-la-pic.s
View File

@ -14,13 +14,15 @@ la $5, symbol($6) # CHECK: lw $5, %got(symbol)($gp) # encoding: [0x8f,0x8
la $6, symbol($6) # CHECK: lw $1, %got(symbol)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addu $6, $1, $6 # encoding: [0x00,0x26,0x30,0x21]
la $5, symbol+8 # CHECK: lw $5, %got(symbol+8)($gp) # encoding: [0x8f,0x85,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $5, symbol+8($6) # CHECK: lw $5, %got(symbol+8)($gp) # encoding: [0x8f,0x85,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $5, symbol+8 # CHECK: lw $5, %got(symbol)($gp) # encoding: [0x8f,0x85,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $5, $5, 8 # encoding: [0x24,0xa5,0x00,0x08]
la $5, symbol+8($6) # CHECK: lw $5, %got(symbol)($gp) # encoding: [0x8f,0x85,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $5, $5, 8 # encoding: [0x24,0xa5,0x00,0x08]
# CHECK: addu $5, $5, $6 # encoding: [0x00,0xa6,0x28,0x21]
la $6, symbol+8($6) # CHECK: lw $1, %got(symbol+8)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $6, symbol+8($6) # CHECK: lw $1, %got(symbol)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $1, $1, 8 # encoding: [0x24,0x21,0x00,0x08]
# CHECK: addu $6, $1, $6 # encoding: [0x00,0x26,0x30,0x21]
la $5, 1f # CHECK: lw $5, %got($tmp0)($gp) # encoding: [0x8f,0x85,A,A]
@ -38,13 +40,15 @@ la $25, symbol($6) # CHECK: lw $25, %got(symbol)($gp) # encoding: [0x8f,0x
la $25, symbol($25) # CHECK: lw $1, %got(symbol)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addu $25, $1, $25 # encoding: [0x00,0x39,0xc8,0x21]
la $25, symbol+8 # CHECK: lw $25, %got(symbol+8)($gp) # encoding: [0x8f,0x99,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $25, symbol+8($6) # CHECK: lw $25, %got(symbol+8)($gp) # encoding: [0x8f,0x99,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $25, symbol+8 # CHECK: lw $25, %got(symbol)($gp) # encoding: [0x8f,0x99,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $25, $25, 8 # encoding: [0x27,0x39,0x00,0x08]
la $25, symbol+8($6) # CHECK: lw $25, %got(symbol)($gp) # encoding: [0x8f,0x99,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $25, $25, 8 # encoding: [0x27,0x39,0x00,0x08]
# CHECK: addu $25, $25, $6 # encoding: [0x03,0x26,0xc8,0x21]
la $25, symbol+8($25) # CHECK: lw $1, %got(symbol+8)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
la $25, symbol+8($25) # CHECK: lw $1, %got(symbol)($gp) # encoding: [0x8f,0x81,A,A]
# CHECK: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK: addiu $1, $1, 8 # encoding: [0x24,0x21,0x00,0x08]
# CHECK: addu $25, $1, $25 # encoding: [0x00,0x39,0xc8,0x21]
la $25, 1f # CHECK: lw $25, %got($tmp1)($gp) # encoding: [0x8f,0x99,A,A]

8
test/MC/Mips/mips-expansions.s
View File

@ -144,13 +144,13 @@
# CHECK-LE: sw $10, -7616($1) # encoding: [0x40,0xe2,0x2a,0xac]
lw $8, symbol+8
# CHECK-LE: lw $8, %got(symbol+8)($gp) # encoding: [A,A,0x88,0x8f]
# CHECK-LE: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
# CHECK-LE: lw $8, %got(symbol)($gp) # encoding: [A,A,0x88,0x8f]
# CHECK-LE: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK-LE: addiu $8, $8, 8 # encoding: [0x08,0x00,0x08,0x25]
# CHECK-LE: lw $8, 0($8) # encoding: [0x00,0x00,0x08,0x8d]
sw $8, symbol+8
# CHECK-LE: lw $1, %got(symbol+8)($gp) # encoding: [A,A,0x81,0x8f]
# CHECK-LE: # fixup A - offset: 0, value: %got(symbol+8), kind: fixup_Mips_GOT
# CHECK-LE: lw $1, %got(symbol)($gp) # encoding: [A,A,0x81,0x8f]
# CHECK-LE: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
# CHECK-LE: addiu $1, $1, 8 # encoding: [0x08,0x00,0x21,0x24]
# CHECK-LE: sw $8, 0($1) # encoding: [0x00,0x00,0x28,0xac]