LLVM Exercise III

Let us return a larger constant:

int foo() {
    return 0xFF;
}

For numbers up to 12 bits we can use the LDI S&X instruction. Some code snippets:

def immSExt12 : PatLeaf<(imm),
                    [{ return isInt<12>(N->getSExtValue()); }]>;

def : Pat<(i32 immSExt12:$in), (LDI imm:$in)>;

def LDI : HP41MCODEInst<0x130, (outs RC:$r), (ins i32imm:$sx),
                        "LDI S&X HEX: $sx",
                        [(set RC:$r, (i32 immSExt12:$sx))]>;

This produces:

	.file	"hello.c"
	.text
	.globl	foo                     ! -- Begin function foo
	.type	foo,@function
foo:                                    ! @foo
! %bb.0:                                ! %entry
	LDI S&X HEX: 0FF
	RTN
.Lfunc_end0:
	.size	foo, .Lfunc_end0-foo
                                        ! -- End function
	.ident	"clang version 20.0.0git (https://github.com/llvm/llvm-project.git ea1dfd50bfdfbd75969fd7653bc71c81f2a2350f)"
	.section	".note.GNU-stack"
	.addrsig