Improve code for passing constant longs as arguments to function calls.

For example, on this instruction:

        call void %test(long 1234)

Instead of this:
        mov %EAX, 1234
        mov %ECX, 0
        mov DWORD PTR [%ESP], %EAX
        mov DWORD PTR [%ESP + 4], %ECX
        call test

We now emit this:
        mov DWORD PTR [%ESP], 1234
        mov DWORD PTR [%ESP + 4], 0
        call test


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12686 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 5 deletions

diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index 1d4b7c97e2..264a1373de 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -1339,11 +1339,19 @@ void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI,
         }
         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),
-                     X86::ESP, ArgOffset+4).addReg(ArgReg+1);
+        if (Args[i].Val && isa<ConstantInt>(Args[i].Val)) {
+          uint64_t Val = cast<ConstantInt>(Args[i].Val)->getRawValue();
+          addRegOffset(BuildMI(BB, X86::MOV32mi, 5),
+                       X86::ESP, ArgOffset).addImm(Val & ~0U);
+          addRegOffset(BuildMI(BB, X86::MOV32mi, 5),
+                       X86::ESP, ArgOffset+4).addImm(Val >> 32ULL);
+        } else {
+          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),
+                       X86::ESP, ArgOffset+4).addReg(ArgReg+1);
+        }
         ArgOffset += 4;        // 8 byte entry, not 4.
         break;