diff options
| author | Chris Lattner <sabre@nondot.org> | 2004-03-01 02:34:08 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2004-03-01 02:34:08 +0000 |
| commit | ce6096f49bd5741a37116e1bf9df501600a631d3 (patch) | |
| tree | 8e8e9282a226a4da0873c94995b4dfce774746a0 /lib/Target/X86/InstSelectSimple.cpp | |
| parent | 99df2579103c1a9f7f93cd8115d29f2294a9010d (diff) | |
Fix a minor code-quality issue. When passing 8 and 16-bit integer constants
to function calls, we would emit dead code, like this:
int Y(int, short, double);
int X() {
Y(4, 123, 4);
}
--- Old
X:
sub %ESP, 20
mov %EAX, 4
mov DWORD PTR [%ESP], %EAX
*** mov %AX, 123
mov %AX, 123
movsx %EAX, %AX
mov DWORD PTR [%ESP + 4], %EAX
fld QWORD PTR [.CPIX_0]
fstp QWORD PTR [%ESP + 8]
call Y
mov %EAX, 0
# IMPLICIT_USE %EAX %ESP
add %ESP, 20
ret
Now we emit:
X:
sub %ESP, 20
mov %EAX, 4
mov DWORD PTR [%ESP], %EAX
mov %AX, 123
movsx %EAX, %AX
mov DWORD PTR [%ESP + 4], %EAX
fld QWORD PTR [.CPIX_0]
fstp QWORD PTR [%ESP + 8]
call Y
mov %EAX, 0
# IMPLICIT_USE %EAX %ESP
add %ESP, 20
ret
Next up, eliminate the mov AX and movsx entirely!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12026 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/X86/InstSelectSimple.cpp')
| -rw-r--r-- | lib/Target/X86/InstSelectSimple.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp index 0aa4ef98da..b7796647d3 100644 --- a/lib/Target/X86/InstSelectSimple.cpp +++ b/lib/Target/X86/InstSelectSimple.cpp @@ -1098,7 +1098,7 @@ void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI, // Arguments go on the stack in reverse order, as specified by the ABI. unsigned ArgOffset = 0; for (unsigned i = 0, e = Args.size(); i != e; ++i) { - unsigned ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg; + unsigned ArgReg; switch (getClassB(Args[i].Ty)) { case cByte: case cShort: { @@ -1110,10 +1110,12 @@ void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI, break; } case cInt: + ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg; addRegOffset(BuildMI(BB, X86::MOV32mr, 5), X86::ESP, ArgOffset).addReg(ArgReg); break; case cLong: + ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg; addRegOffset(BuildMI(BB, X86::MOV32mr, 5), X86::ESP, ArgOffset).addReg(ArgReg); addRegOffset(BuildMI(BB, X86::MOV32mr, 5), @@ -1122,6 +1124,7 @@ void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI, break; case cFP: + ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg; if (Args[i].Ty == Type::FloatTy) { addRegOffset(BuildMI(BB, X86::FST32m, 5), X86::ESP, ArgOffset).addReg(ArgReg); |