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[mips] Reduce number of instructions used for loading a global symbol's value
Now `lw/sw $reg, sym+offset` pseudo instructions for global symbol `sym` are lowering into the following three instructions. ``` lw $reg, %got(symbol)($gp) addiu $reg, $reg, offset lw/sw $reg, 0($reg) ``` It's possible to reduce the number of instructions by taking the offset in account in the final `lw/sw` command. This patch implements that optimization. ``` lw $reg, %got(symbol)($gp) lw/sw $reg, offset($reg) ``` Differential Revision: https://reviews.llvm.org/D66553 llvm-svn: 369756
This commit is contained in:
Simon Atanasyan
parent
493b163f5d
commit
d52b14937d
@ -3655,17 +3655,25 @@ void MipsAsmParser::expandMemInst(MCInst &Inst, SMLoc IDLoc, MCStreamer &Out,
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if (inPicMode()) {
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// FIXME:
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// a) Fix lw/sw $reg, symbol($reg) instruction expanding.
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// b) If expression includes offset (sym + number), do not
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// encode the offset into a relocation. Take it in account
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// in the last load/store instruction.
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// c) Check that immediates of R_MIPS_GOT16/R_MIPS_LO16 relocations
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// do not exceed 16-bit.
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// d) Use R_MIPS_GOT_PAGE/R_MIPS_GOT_OFST relocations instead
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// of R_MIPS_GOT_DISP in appropriate cases to reduce number
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// of GOT entries.
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loadAndAddSymbolAddress(OffsetOp.getExpr(), TmpReg, Mips::NoRegister,
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MCValue Res;
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if (!OffsetOp.getExpr()->evaluateAsRelocatable(Res, nullptr, nullptr)) {
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Error(IDLoc, "expected relocatable expression");
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return;
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}
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if (Res.getSymB() != nullptr) {
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Error(IDLoc, "expected relocatable expression with only one symbol");
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return;
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}
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loadAndAddSymbolAddress(Res.getSymA(), TmpReg, Mips::NoRegister,
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!ABI.ArePtrs64bit(), IDLoc, Out, STI);
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TOut.emitRRI(Inst.getOpcode(), DstReg, TmpReg, 0, IDLoc, STI);
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TOut.emitRRI(Inst.getOpcode(), DstReg, TmpReg, Res.getConstant(), IDLoc,
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STI);
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} else {
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const MCExpr *ExprOffset = OffsetOp.getExpr();
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MCOperand LoOperand = MCOperand::createExpr(
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@ -122,17 +122,17 @@
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# CHECK-LE: sw $10, 0($1) # encoding: [0x00,0x00,0x2a,0xac]
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lw $8, 1f+8
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# CHECK-LE: lw $8, %got(($tmp0)+8)($gp) # encoding: [A,A,0x88,0x8f]
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# CHECK-LE: # fixup A - offset: 0, value: %got(($tmp0)+8), kind: fixup_Mips_GOT
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# CHECK-LE: addiu $8, $8, %lo(($tmp0)+8) # encoding: [A,A,0x08,0x25]
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# CHECK-LE: # fixup A - offset: 0, value: %lo(($tmp0)+8), kind: fixup_Mips_LO16
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# CHECK-LE: lw $8, 0($8) # encoding: [0x00,0x00,0x08,0x8d]
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# CHECK-LE: lw $8, %got($tmp0)($gp) # encoding: [A,A,0x88,0x8f]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %got($tmp0), kind: fixup_Mips_GOT
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# CHECK-LE-NEXT: addiu $8, $8, %lo($tmp0) # encoding: [A,A,0x08,0x25]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %lo($tmp0), kind: fixup_Mips_LO16
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# CHECK-LE-NEXT: lw $8, 8($8) # encoding: [0x08,0x00,0x08,0x8d]
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sw $8, 1f+8
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# CHECK-LE: lw $1, %got(($tmp0)+8)($gp) # encoding: [A,A,0x81,0x8f]
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# CHECK-LE: # fixup A - offset: 0, value: %got(($tmp0)+8), kind: fixup_Mips_GOT
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# CHECK-LE: addiu $1, $1, %lo(($tmp0)+8) # encoding: [A,A,0x21,0x24]
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# CHECK-LE: # fixup A - offset: 0, value: %lo(($tmp0)+8), kind: fixup_Mips_LO16
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# CHECK-LE: sw $8, 0($1) # encoding: [0x00,0x00,0x28,0xac]
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# CHECK-LE: lw $1, %got($tmp0)($gp) # encoding: [A,A,0x81,0x8f]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %got($tmp0), kind: fixup_Mips_GOT
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# CHECK-LE-NEXT: addiu $1, $1, %lo($tmp0) # encoding: [A,A,0x21,0x24]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %lo($tmp0), kind: fixup_Mips_LO16
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# CHECK-LE-NEXT: sw $8, 8($1) # encoding: [0x08,0x00,0x28,0xac]
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lw $10, 655483($4)
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# CHECK-LE: lui $10, 10 # encoding: [0x0a,0x00,0x0a,0x3c]
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@ -144,15 +144,13 @@
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# CHECK-LE: sw $10, -7616($1) # encoding: [0x40,0xe2,0x2a,0xac]
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lw $8, symbol+8
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# CHECK-LE: lw $8, %got(symbol)($gp) # encoding: [A,A,0x88,0x8f]
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# CHECK-LE: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
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# CHECK-LE: addiu $8, $8, 8 # encoding: [0x08,0x00,0x08,0x25]
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# CHECK-LE: lw $8, 0($8) # encoding: [0x00,0x00,0x08,0x8d]
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# CHECK-LE: lw $8, %got(symbol)($gp) # encoding: [A,A,0x88,0x8f]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
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# CHECK-LE-NEXT: lw $8, 8($8) # encoding: [0x08,0x00,0x08,0x8d]
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sw $8, symbol+8
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# CHECK-LE: lw $1, %got(symbol)($gp) # encoding: [A,A,0x81,0x8f]
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# CHECK-LE: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
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# CHECK-LE: addiu $1, $1, 8 # encoding: [0x08,0x00,0x21,0x24]
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# CHECK-LE: sw $8, 0($1) # encoding: [0x00,0x00,0x28,0xac]
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# CHECK-LE: lw $1, %got(symbol)($gp) # encoding: [A,A,0x81,0x8f]
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# CHECK-LE-NEXT: # fixup A - offset: 0, value: %got(symbol), kind: fixup_Mips_GOT
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# CHECK-LE-NEXT: sw $8, 8($1) # encoding: [0x08,0x00,0x28,0xac]
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ldc1 $f0, symbol
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# CHECK-LE: lw $1, %got(symbol)($gp) # encoding: [A,A,0x81,0x8f]
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@ -481,15 +481,13 @@ sym:
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# CHECK: sw $10, 0($1) # encoding: [0x00,0x00,0x2a,0xac]
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lw $8, sym+8
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# CHECK: ld $8, %got_disp(sym)($gp) # encoding: [A,A,0x88,0xdf]
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# CHECK: # fixup A - offset: 0, value: %got_disp(sym), kind: fixup_Mips_GOT_DISP
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# CHECK: daddiu $8, $8, 8 # encoding: [0x08,0x00,0x08,0x65]
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# CHECK: lw $8, 0($8) # encoding: [0x00,0x00,0x08,0x8d]
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# CHECK: ld $8, %got_disp(sym)($gp) # encoding: [A,A,0x88,0xdf]
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# CHECK-NEXT: # fixup A - offset: 0, value: %got_disp(sym), kind: fixup_Mips_GOT_DISP
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# CHECK-NEXT: lw $8, 8($8) # encoding: [0x08,0x00,0x08,0x8d]
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sw $8, sym+8
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# CHECK: ld $1, %got_disp(sym)($gp) # encoding: [A,A,0x81,0xdf]
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# CHECK: # fixup A - offset: 0, value: %got_disp(sym), kind: fixup_Mips_GOT_DISP
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# CHECK: daddiu $1, $1, 8 # encoding: [0x08,0x00,0x21,0x64]
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# CHECK: sw $8, 0($1) # encoding: [0x00,0x00,0x28,0xac]
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# CHECK: ld $1, %got_disp(sym)($gp) # encoding: [A,A,0x81,0xdf]
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# CHECK-NEXT: # fixup A - offset: 0, value: %got_disp(sym), kind: fixup_Mips_GOT_DISP
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# CHECK-NEXT: sw $8, 8($1) # encoding: [0x08,0x00,0x28,0xac]
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lw $10, 655483($4)
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# CHECK: lui $10, 10 # encoding: [0x0a,0x00,0x0a,0x3c]
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@ -501,15 +499,13 @@ sym:
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# CHECK: sw $10, -7616($1) # encoding: [0x40,0xe2,0x2a,0xac]
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lw $8, symbol+8
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# CHECK: ld $8, %got_disp(symbol)($gp) # encoding: [A,A,0x88,0xdf]
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# CHECK: # fixup A - offset: 0, value: %got_disp(symbol), kind: fixup_Mips_GOT_DISP
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# CHECK: daddiu $8, $8, 8 # encoding: [0x08,0x00,0x08,0x65]
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# CHECK: lw $8, 0($8) # encoding: [0x00,0x00,0x08,0x8d]
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# CHECK: ld $8, %got_disp(symbol)($gp) # encoding: [A,A,0x88,0xdf]
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# CHECK-NEXT: # fixup A - offset: 0, value: %got_disp(symbol), kind: fixup_Mips_GOT_DISP
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# CHECK-NEXT: lw $8, 8($8) # encoding: [0x08,0x00,0x08,0x8d]
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sw $8, symbol+8
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# CHECK: ld $1, %got_disp(symbol)($gp) # encoding: [A,A,0x81,0xdf]
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# CHECK: # fixup A - offset: 0, value: %got_disp(symbol), kind: fixup_Mips_GOT_DISP
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# CHECK: daddiu $1, $1, 8 # encoding: [0x08,0x00,0x21,0x64]
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# CHECK: sw $8, 0($1) # encoding: [0x00,0x00,0x28,0xac]
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# CHECK: ld $1, %got_disp(symbol)($gp) # encoding: [A,A,0x81,0xdf]
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# CHECK-NEXT: # fixup A - offset: 0, value: %got_disp(symbol), kind: fixup_Mips_GOT_DISP
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# CHECK-NEXT: sw $8, 8($1) # encoding: [0x08,0x00,0x28,0xac]
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ldc1 $f0, symbol
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# CHECK: ld $1, %got_disp(symbol)($gp) # encoding: [A,A,0x81,0xdf]
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