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InstSelectSimple.cpp: Add some comments that say what I'm going to do for
 calls and casts.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4832 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Brian Gaeke 2002-11-26 10:43:30 +00:00
parent e31267dd9a
commit c11232a8c4
2 changed files with 66 additions and 6 deletions
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36
lib/Target/X86/InstSelectSimple.cpp
View File

@ -363,9 +363,9 @@ ISel::visitBranchInst (BranchInst & BI)
}
}
void
ISel::visitCallInst (CallInst &CI)
{
/// visitCallInst - Have to push args and do a procedure call
/// instruction, if the target address is known.
void ISel::visitCallInst (CallInst &CI) {
visitInstruction (CI);
}
@ -581,9 +581,39 @@ void ISel::visitPHINode(PHINode &PN) {
}
}
/// visitCastInst - Here we have various kinds of copying with or without
/// sign extension going on.
void
ISel::visitCastInst (CastInst &CI)
{
//> cast larger int to smaller int --> copy least significant byte/word w/ mov?
//
//I'm not really sure what to do with this. We could insert a pseudo-op
//that says take the low X bits of a Y bit register, but for now we can just
//force the value into, say, EAX, then rip out AL or AX. The advantage of
//the former is that the register allocator could use any register it wants,
//but for now this obviously doesn't matter. :)
// if target type is bool
// Emit Compare
// Emit Set-if-not-zero
// if size of target type == size of source type
// Emit Mov reg(target) <- reg(source)
// if size of target type > size of source type
// if both types are integer types
// if source type is signed
// sbyte to short, ushort: Emit movsx 8->16
// sbyte to int, uint: Emit movsx 8->32
// short to int, uint: Emit movsx 16->32
// else if source type is unsigned
// ubyte to short, ushort: Emit movzx 8->16
// ubyte to int, uint: Emit movzx 8->32
// ushort to int, uint: Emit movzx 16->32
// if both types are fp types
// float to double: Emit fstp, fld (???)
visitInstruction (CI);
}

36
lib/Target/X86/X86ISelSimple.cpp
View File

@ -363,9 +363,9 @@ ISel::visitBranchInst (BranchInst & BI)
}
}
void
ISel::visitCallInst (CallInst &CI)
{
/// visitCallInst - Have to push args and do a procedure call
/// instruction, if the target address is known.
void ISel::visitCallInst (CallInst &CI) {
visitInstruction (CI);
}
@ -581,9 +581,39 @@ void ISel::visitPHINode(PHINode &PN) {
}
}
/// visitCastInst - Here we have various kinds of copying with or without
/// sign extension going on.
void
ISel::visitCastInst (CastInst &CI)
{
//> cast larger int to smaller int --> copy least significant byte/word w/ mov?
//
//I'm not really sure what to do with this. We could insert a pseudo-op
//that says take the low X bits of a Y bit register, but for now we can just
//force the value into, say, EAX, then rip out AL or AX. The advantage of
//the former is that the register allocator could use any register it wants,
//but for now this obviously doesn't matter. :)
// if target type is bool
// Emit Compare
// Emit Set-if-not-zero
// if size of target type == size of source type
// Emit Mov reg(target) <- reg(source)
// if size of target type > size of source type
// if both types are integer types
// if source type is signed
// sbyte to short, ushort: Emit movsx 8->16
// sbyte to int, uint: Emit movsx 8->32
// short to int, uint: Emit movsx 16->32
// else if source type is unsigned
// ubyte to short, ushort: Emit movzx 8->16
// ubyte to int, uint: Emit movzx 8->32
// ushort to int, uint: Emit movzx 16->32
// if both types are fp types
// float to double: Emit fstp, fld (???)
visitInstruction (CI);
}