Add some very basic support for the Intel32 ABI.

In 32-bit mode, all function arguments are passed on the stack, not in
registers.

This ABI support is not complete or properly tested, but at least it
doesn't try to pass arguments in r8.

cranelift/filetests/isa/intel/abi32.cton

@@ -0,0 +1,20 @@
+; Test the legalization of function signatures.
+test legalizer
+isa intel
+
+; regex: V=v\d+
+
+function %f() {
+    sig0 = (i32) -> i32 native
+    ; check: sig0 = (i32 [0]) -> i32 [%rax] native
+
+    sig1 = (i64) -> b1 native
+    ; check: sig1 = (i32 [0], i32 [4]) -> b1 [%rax] native
+
+    sig2 = (f32, i64) -> f64 native
+    ; check: sig2 = (f32 [0], i32 [4], i32 [8]) -> f64 [%xmm0] native
+
+ebb0:
+    return
+}
+

cranelift/filetests/isa/intel/legalize-custom.cton

@@ -11,7 +11,7 @@ function %cond_trap(i32) {
 ebb0(v1: i32):
     trapz v1, user67
     return
-    ; check: $ebb0($v1: i32):
+    ; check: $ebb0($v1: i32
     ; nextln: brnz $v1, $(new=$EBB)
     ; nextln: trap user67
     ; check: $new:
@@ -22,7 +22,7 @@ function %cond_trap2(i32) {
 ebb0(v1: i32):
     trapnz v1, int_ovf
     return
-    ; check: $ebb0($v1: i32):
+    ; check: $ebb0($v1: i32
     ; nextln: brz $v1, $(new=$EBB)
     ; nextln: trap int_ovf
     ; check: $new:
@@ -34,7 +34,7 @@ ebb0(v1: i32):
     v2 = icmp_imm eq v1, 6
     trapz v2, user7
     return
-    ; check: $ebb0($v1: i32):
+    ; check: $ebb0($v1: i32
     ; check: brnz $v2, $(new=$EBB)
     ; nextln: trap user7
     ; check: $new:
@@ -46,7 +46,7 @@ ebb0(v1: i32):
     v2 = icmp_imm eq v1, 6
     trapnz v2, user9
     return
-    ; check: $ebb0($v1: i32):
+    ; check: $ebb0($v1: i32
     ; check: brz $v2, $(new=$EBB)
     ; nextln: trap user9
     ; check: $new:

cranelift/filetests/regalloc/intel-regres.cton

@@ -38,3 +38,9 @@ ebb2(v4: i32, v5: i32, v7: i32):
 ebb3:
     return v5
 }
+
+function %select_i64(i64, i64, i32) -> i64 {
+ebb0(v0: i64, v1: i64, v2: i32):
+    v3 = select v2, v0, v1
+    return v3
+}

lib/cretonne/src/isa/intel/abi.rs

@@ -106,9 +106,17 @@ impl ArgAssigner for Args {
 
 /// Legalize `sig`.
 pub fn legalize_signature(sig: &mut ir::Signature, flags: &shared_settings::Flags, _current: bool) {
-    let bits = if flags.is_64bit() { 64 } else { 32 };
+    let bits;
+    let mut args;
+
+    if flags.is_64bit() {
+        bits = 64;
+        args = Args::new(bits, &ARG_GPRS, 8);
+    } else {
+        bits = 32;
+        args = Args::new(bits, &[], 0);
+    }
 
-    let mut args = Args::new(bits, &ARG_GPRS, 8);
     legalize_args(&mut sig.argument_types, &mut args);
 
     let mut rets = Args::new(bits, &RET_GPRS, 2);