[m-rev.] post-commit diff: fix bug in dupelim.m

[Peter Wang]

Discussed with Zoltan in person.  It's possibly not a 100% fix
but committed it for now.


Estimated hours taken: 1.5
Branches: main, release

Fix a compiler abort when `--optimise-dups' detects some duplicate code
sequences in parallel conjunctions.

compiler/dupelim.m:
	Allow `most_specific_instr' to generalise two `fork',
	`init_sync_term', `join_and_continue' or `join_and_terminate'
	instructions if they take exactly the same arguments.

tests/valid/Mercury.options:
tests/valid/Mmakefile:
tests/valid/par_dupelim.m:
	Add a test case.

Index: compiler/dupelim.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/dupelim.m,v
retrieving revision 1.78
diff -u -r1.78 dupelim.m
--- compiler/dupelim.m	26 Apr 2006 03:05:33 -0000	1.78
+++ compiler/dupelim.m	28 Apr 2006 08:25:41 -0000
@@ -756,6 +756,10 @@
         ; Instr1 = decr_sp(_)
         ; Instr1 = decr_sp_and_return(_)
         ; Instr1 = pragma_c(_, _, _, _, _, _, _, _, _)
+        ; Instr1 = fork(_, _, _)
+        ; Instr1 = init_sync_term(_, _)
+        ; Instr1 = join_and_continue(_, _)
+        ; Instr1 = join_and_terminate(_)
         ),
         ( Instr1 = Instr2 ->
             MaybeInstr = yes(Instr1)
@@ -763,12 +767,7 @@
             MaybeInstr = no
         )
     ;
-        ( Instr1 = comment(_)
-        ; Instr1 = fork(_, _, _)
-        ; Instr1 = init_sync_term(_, _)
-        ; Instr1 = join_and_continue(_, _)
-        ; Instr1 = join_and_terminate(_)
-        ),
+        Instr1 = comment(_),
         MaybeInstr = no
     ).
 
Index: tests/valid/Mercury.options
===================================================================
RCS file: /home/mercury1/repository/tests/valid/Mercury.options,v
retrieving revision 1.31
diff -u -r1.31 Mercury.options
--- tests/valid/Mercury.options	28 Apr 2006 04:13:23 -0000	1.31
+++ tests/valid/Mercury.options	4 May 2006 04:10:13 -0000
@@ -93,6 +93,7 @@
 MCFLAGS-mostly_uniq_mode_inf	= --infer-all
 MCFLAGS-mpj6			= --infer-all
 MCFLAGS-no_warn_obsolete	= --no-warn-obsolete
+MCFLAGS-par_dupelim		= --optimize-dups
 MCFLAGS-par_saved_const 	= -O3 --optimize-saved-vars-const
 MCFLAGS-pred_with_no_modes	= --infer-all
 MCFLAGS-quantifier_warning	= --halt-at-warn
Index: tests/valid/Mmakefile
===================================================================
RCS file: /home/mercury1/repository/tests/valid/Mmakefile,v
retrieving revision 1.173
diff -u -r1.173 Mmakefile
--- tests/valid/Mmakefile	20 Apr 2006 03:57:21 -0000	1.173
+++ tests/valid/Mmakefile	4 May 2006 04:06:16 -0000
@@ -228,7 +228,8 @@
 # These tests only work in grades that support parallel conjunction.
 #
 PAR_CONJ_PROGS = \
-	par_dummy
+	par_dummy \
+	par_dupelim
 
 # The following programs require that num_tag_bits >= 1
 RESERVE_TAG_PROGS = \
Index: tests/valid/par_dupelim.m
===================================================================
RCS file: tests/valid/par_dupelim.m
diff -N tests/valid/par_dupelim.m
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tests/valid/par_dupelim.m	4 May 2006 04:05:03 -0000
@@ -0,0 +1,25 @@
+% Uncaught Mercury exception:
+% Software Error: dupelim.m: Unexpected: blocks with same standard 
+%   form don't antiunify
+
+:- module par_dupelim.
+:- interface.
+
+:- type t ---> t1 ; t2.
+:- pred p(t::in, int::out) is det.
+
+:- implementation.
+
+p(T, X) :-
+    (
+	T = t1,
+	( X = 1
+	& true
+	% This conjunct is the same as a later conjunct.
+	)
+    ;
+	T = t2,
+	( X = 2
+	& true
+	)
+    ).
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