Implement some relaxations for arithmetic instructions. The limitation
on RIP relative relocations looks artificial, but this is a superset of
what we were able to do before.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117364 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86AsmBackend.cpp b/lib/Target/X86/X86AsmBackend.cpp
index be56719..687971d 100644
--- a/lib/Target/X86/X86AsmBackend.cpp
+++ b/lib/Target/X86/X86AsmBackend.cpp
@@ -69,16 +69,11 @@
};
} // end anonymous namespace
-static unsigned getRelaxedOpcode(unsigned Op) {
+static unsigned getRelaxedOpcodeBranch(unsigned Op) {
switch (Op) {
default:
return Op;
- // This is used on i386 with things like addl $foo, %ebx
- // FIXME: Should the other *i8 instructions be here too? If not, it might
- // be better to just select X86::ADD32ri instead of X86::ADD32ri8.
- case X86::ADD32ri8: return X86::ADD32ri;
-
case X86::JAE_1: return X86::JAE_4;
case X86::JA_1: return X86::JA_4;
case X86::JBE_1: return X86::JBE_4;
@@ -99,16 +94,101 @@
}
}
+static unsigned getRelaxedOpcodeArith(unsigned Op) {
+ switch (Op) {
+ default:
+ return Op;
+
+ // IMUL
+ case X86::IMUL16rri8: return X86::IMUL16rri;
+ case X86::IMUL16rmi8: return X86::IMUL16rmi;
+ case X86::IMUL32rri8: return X86::IMUL32rri;
+ case X86::IMUL32rmi8: return X86::IMUL32rmi;
+ case X86::IMUL64rri8: return X86::IMUL64rri32;
+ case X86::IMUL64rmi8: return X86::IMUL64rmi32;
+
+ // AND
+ case X86::AND16ri8: return X86::AND16ri;
+ case X86::AND16mi8: return X86::AND16mi;
+ case X86::AND32ri8: return X86::AND32ri;
+ case X86::AND32mi8: return X86::AND32mi;
+ case X86::AND64ri8: return X86::AND64ri32;
+ case X86::AND64mi8: return X86::AND64mi32;
+
+ // OR
+ case X86::OR16ri8: return X86::OR16ri;
+ case X86::OR16mi8: return X86::OR16mi;
+ case X86::OR32ri8: return X86::OR32ri;
+ case X86::OR32mi8: return X86::OR32mi;
+ case X86::OR64ri8: return X86::OR64ri32;
+ case X86::OR64mi8: return X86::OR64mi32;
+
+ // XOR
+ case X86::XOR16ri8: return X86::XOR16ri;
+ case X86::XOR16mi8: return X86::XOR16mi;
+ case X86::XOR32ri8: return X86::XOR32ri;
+ case X86::XOR32mi8: return X86::XOR32mi;
+ case X86::XOR64ri8: return X86::XOR64ri32;
+ case X86::XOR64mi8: return X86::XOR64mi32;
+
+ // ADD
+ case X86::ADD16ri8: return X86::ADD16ri;
+ case X86::ADD16mi8: return X86::ADD16mi;
+ case X86::ADD32ri8: return X86::ADD32ri;
+ case X86::ADD32mi8: return X86::ADD32mi;
+ case X86::ADD64ri8: return X86::ADD64ri32;
+ case X86::ADD64mi8: return X86::ADD64mi32;
+
+ // SUB
+ case X86::SUB16ri8: return X86::SUB16ri;
+ case X86::SUB16mi8: return X86::SUB16mi;
+ case X86::SUB32ri8: return X86::SUB32ri;
+ case X86::SUB32mi8: return X86::SUB32mi;
+ case X86::SUB64ri8: return X86::SUB64ri32;
+ case X86::SUB64mi8: return X86::SUB64mi32;
+
+ // CMP
+ case X86::CMP16ri8: return X86::CMP16ri;
+ case X86::CMP16mi8: return X86::CMP16mi;
+ case X86::CMP32ri8: return X86::CMP32ri;
+ case X86::CMP32mi8: return X86::CMP32mi;
+ case X86::CMP64ri8: return X86::CMP64ri32;
+ case X86::CMP64mi8: return X86::CMP64mi32;
+ }
+}
+
+static unsigned getRelaxedOpcode(unsigned Op) {
+ unsigned R = getRelaxedOpcodeArith(Op);
+ if (R != Op)
+ return R;
+ return getRelaxedOpcodeBranch(Op);
+}
+
bool X86AsmBackend::MayNeedRelaxation(const MCInst &Inst) const {
+ // Branches can always be relaxed.
+ if (getRelaxedOpcodeBranch(Inst.getOpcode()) != Inst.getOpcode())
+ return true;
+
// Check if this instruction is ever relaxable.
- if (getRelaxedOpcode(Inst.getOpcode()) == Inst.getOpcode())
+ if (getRelaxedOpcodeArith(Inst.getOpcode()) == Inst.getOpcode())
return false;
- // If so, just assume it can be relaxed. Once we support relaxing more complex
- // instructions we should check that the instruction actually has symbolic
- // operands before doing this, but we need to be careful about things like
- // PCrel.
- return true;
+
+ // Check if it has an expression and is not RIP relative.
+ bool hasExp = false;
+ bool hasRIP = false;
+ for (unsigned i = 0; i < Inst.getNumOperands(); ++i) {
+ const MCOperand &Op = Inst.getOperand(i);
+ if (Op.isExpr())
+ hasExp = true;
+
+ if (Op.isReg() && Op.getReg() == X86::RIP)
+ hasRIP = true;
+ }
+
+ // FIXME: Why exactly do we need the !hasRIP? Is it just a limitation on
+ // how we do relaxations?
+ return hasExp && !hasRIP;
}
// FIXME: Can tblgen help at all here to verify there aren't other instructions