diff lab4/test/nasty.p @ 0:bfdcc3820b32

Basis
author Mike Spivey <mike@cs.ox.ac.uk>
date Thu, 05 Oct 2017 08:04:15 +0100
parents
children
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lab4/test/nasty.p	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,75 @@
+(* Order of evaluation and unnesting of procedure calls *)
+
+var x, y, z: integer;
+
+proc nasty(x: integer): integer;
+begin
+  y := 1;
+  return 2 * x;
+end;
+
+begin
+  x := 3; y := 5;
+  z := y + nasty(x);
+  print_num(z); newline()
+end.
+
+(* Gives 7 without optimisation owing to lifting of procedure call;
+   with full CSE, gives 11 because the two occurrences of y can share. *)
+
+(*<<
+11
+>>*)
+
+(*[[
+@ picoPascal compiler output
+	.include "fixup.s"
+	.global pmain
+
+@ proc nasty(x: integer): integer;
+	.text
+_nasty:
+	mov ip, sp
+	stmfd sp!, {r0-r1}
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   y := 1;
+	mov r0, #1
+	set r1, _y
+	str r0, [r1]
+@   return 2 * x;
+	ldr r0, [fp, #40]
+	lsl r0, r0, #1
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+pmain:
+	mov ip, sp
+	stmfd sp!, {r4-r10, fp, ip, lr}
+	mov fp, sp
+@   x := 3; y := 5;
+	mov r4, #3
+	set r0, _x
+	str r4, [r0]
+	mov r5, #5
+	set r0, _y
+	str r5, [r0]
+@   z := y + nasty(x);
+	mov r0, r4
+	bl _nasty
+	add r4, r5, r0
+	set r0, _z
+	str r4, [r0]
+@   print_num(z); newline()
+	mov r0, r4
+	bl print_num
+	bl newline
+	ldmfd fp, {r4-r10, fp, sp, pc}
+	.ltorg
+
+	.comm _x, 4, 4
+	.comm _y, 4, 4
+	.comm _z, 4, 4
+@ End
+]]*)
+