------- Comment #11 from spop at gcc dot gnu dot org 2007-06-17 19:13 -------
Subject: Re: [4.3 Regression] internal compiler error: in
build_polynomial_chrec, at tree-chrec.h:113
The ptrplus patch contains the following code:
*************** interpret_rhs_modify_stmt (struct loop *
*** 1611,1616 ****
--- 1615,1630 ----
switch (TREE_CODE (opnd1))
{
+ case POINTER_PLUS_EXPR:
+ opnd10 = TREE_OPERAND (opnd1, 0);
+ opnd11 = TREE_OPERAND (opnd1, 1);
+ chrec10 = analyze_scalar_evolution (loop, opnd10);
+ chrec11 = analyze_scalar_evolution (loop, opnd11);
+ chrec10 = chrec_convert (type, chrec10, at_stmt);
+ chrec11 = chrec_convert (sizetype, chrec11, at_stmt);
+ res = chrec_fold_plus (type, chrec10, chrec11);
+ break;
+
case PLUS_EXPR:
opnd10 = TREE_OPERAND (opnd1, 0);
opnd11 = TREE_OPERAND (opnd1, 1);
At this point we have the following values:
(gdb) call debug_generic_expr (chrec10)
{ptr_7, +, (unsigned int) (n_20 + 65535) * 4}_1
(gdb) call debug_generic_expr (chrec11)
(unsigned int) {n_6 + 65535, +, 1}_1 * 4
(gdb) call debug_generic_expr (res)
{ptr_7 + (unsigned int) {n_6 + 65535, +, 1}_1 * 4, +, (unsigned int)
(n_20 + 65535) * 4}_1
chrec_fold_plus is completely disturbed by the "complicated" MULT_EXPR
"{}_1 * 4", and just considers this expression to be constant, and
finally it builds "ptr_7 + (unsigned int) {n_6 + 65535, +, 1}_1 * 4".
The code in chrec_fold_multiply that is producing this MULT_EXPR is:
return fold_build2 (MULT_EXPR, type, op0, op1);
(gdb) p op0
$42 = (tree) 0xb7c27444
(gdb) pgs
4
(gdb) p op1
$43 = (tree) 0xb7ccf6a0
(gdb) pgs
(unsigned int) (n_20 + 65535);
(gdb) pt
<nop_expr 0xb7ccf6a0
type <integer_type 0xb7c36000 unsigned int public unsigned sizetype SI
size <integer_cst 0xb7c27658 constant invariant 32>
unit size <integer_cst 0xb7c27444 constant invariant 4>
align 32 symtab 0 alias set -1 canonical type 0xb7c3c0d8
precision 32 min <integer_cst 0xb7c27674 0> max <integer_cst
0xb7c27c08 -1>>
arg 0 <plus_expr 0xb7c2d948
type <integer_type 0xb7c36288 short unsigned int
sizes-gimplified public unsigned HI
size <integer_cst 0xb7c275b0 constant invariant 16>
unit size <integer_cst 0xb7c275cc constant invariant 2>
align 16 symtab 0 alias set -1 canonical type 0xb7c36288
precision 16 min <integer_cst 0xb7c275e8 0> max <integer_cst
0xb7c27594 65535>>
arg 0 <ssa_name 0xb7cdb5e4 type <integer_type 0xb7c36288 short
unsigned int>
var <var_decl 0xb7cd70b8 n> def_stmt <gimple_modify_stmt
0xb7cda770>
version 20>
arg 1 <integer_cst 0xb7c27594 constant invariant 65535>>>
And here, unfortunately fold_build2 does not further simplify this
expression because of the cast to uint around the PLUS_EXPR.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32367
