BuildMI(BB, X86::RET, 0);
}
-
/// visitBranchInst - Handle conditional and unconditional branches here. Note
/// that since code layout is frozen at this point, that if we are trying to
/// jump to a block that is the immediate successor of the current block, we can
/// just make a fall-through. (but we don't currently).
///
-void ISel::visitBranchInst(BranchInst &BI) {
- if (BI.isConditional()) // Only handles unconditional branches so far...
- visitInstruction(BI);
-
- BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(0));
+void
+ISel::visitBranchInst (BranchInst & BI)
+{
+ if (BI.isConditional ())
+ {
+ BasicBlock *ifTrue = BI.getSuccessor (0);
+ BasicBlock *ifFalse = BI.getSuccessor (1); // this is really unobvious
+
+ // simplest thing I can think of: compare condition with zero,
+ // followed by jump-if-equal to ifFalse, and jump-if-nonequal to
+ // ifTrue
+ unsigned int condReg = getReg (BI.getCondition ());
+ BuildMI (BB, X86::CMPri8, 2, X86::EFLAGS).addReg (condReg).addZImm (0);
+ BuildMI (BB, X86::JNE, 1).addPCDisp (BI.getSuccessor (0));
+ BuildMI (BB, X86::JE, 1).addPCDisp (BI.getSuccessor (1));
+ }
+ else // unconditional branch
+ {
+ BuildMI (BB, X86::JMP, 1).addPCDisp (BI.getSuccessor (0));
+ }
}
BuildMI(BB, X86::RET, 0);
}
-
/// visitBranchInst - Handle conditional and unconditional branches here. Note
/// that since code layout is frozen at this point, that if we are trying to
/// jump to a block that is the immediate successor of the current block, we can
/// just make a fall-through. (but we don't currently).
///
-void ISel::visitBranchInst(BranchInst &BI) {
- if (BI.isConditional()) // Only handles unconditional branches so far...
- visitInstruction(BI);
-
- BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(0));
+void
+ISel::visitBranchInst (BranchInst & BI)
+{
+ if (BI.isConditional ())
+ {
+ BasicBlock *ifTrue = BI.getSuccessor (0);
+ BasicBlock *ifFalse = BI.getSuccessor (1); // this is really unobvious
+
+ // simplest thing I can think of: compare condition with zero,
+ // followed by jump-if-equal to ifFalse, and jump-if-nonequal to
+ // ifTrue
+ unsigned int condReg = getReg (BI.getCondition ());
+ BuildMI (BB, X86::CMPri8, 2, X86::EFLAGS).addReg (condReg).addZImm (0);
+ BuildMI (BB, X86::JNE, 1).addPCDisp (BI.getSuccessor (0));
+ BuildMI (BB, X86::JE, 1).addPCDisp (BI.getSuccessor (1));
+ }
+ else // unconditional branch
+ {
+ BuildMI (BB, X86::JMP, 1).addPCDisp (BI.getSuccessor (0));
+ }
}
// Flow control instructions
I(RET , "ret", 0xCB, M_RET_FLAG, X86II::RawFrm | X86II::Void) // ret
I(JMP , "jmp", 0x00, M_BRANCH_FLAG, X86II::Void) // jmp foo EB|E9 cb|w
+I(JNE , "jne", 0x00, M_BRANCH_FLAG, X86II::Void) // 75 cb, or 0f 85 cw|cd
+I(JE , "je", 0x00, M_BRANCH_FLAG, X86II::Void) // 74 cb, or 0f 84 cw|cd
// Misc instructions
I(LEAVE , "leave", 0xC9, 0, X86II::RawFrm) // leave
I(CMPrr8 , "cmpb", 0x38, 0, X86II::MRMDestReg) // compare R8,R8 38/r
I(CMPrr16 , "cmpw", 0x39, 0, X86II::MRMDestReg) // compare R16,R16 39/r
I(CMPrr32 , "cmpl", 0x39, 0, X86II::MRMDestReg) // compare R32,R32 39/r
+I(CMPri8 , "cmp", 0x80, 0, 0) // compare R8, imm8 80 /7 ib
// Sign extenders (first 3 are good for DIV/IDIV; the others are more general)
I(CBW , "cbw", 0x98, 0, X86II::RawFrm) // AX = signext(AL)