[Bug middle-end/51769] New: bootstrap fails when using -O2 -funswitch-loops -floop-flatten

[Bug middle-end/51769] New: bootstrap fails when using -O2 -funswitch-loops -floop-flatten

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51769

             Bug #: 51769
           Summary: bootstrap fails when using  -O2 -funswitch-loops
                    -floop-flatten
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: matt@use.net


Bootstrap has failed for at least a few months now when adding -floop-flatten
and other options. I've filed several other bugs where loop-flatten with other
options causes the same ICE across other popular open source projects: PR50398
and PR50561 come to mind.

To reproduce:

g++
-I/tmp/gcc-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include/x86_64-unknown-linux-gnu
-I/tmp/gcc-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include
-I/home/matt/src/gcc-4.7.0/libstdc++-v3/libsupc++
-L/tmp/gcc-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs
-L/tmp/gcc-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs -c  
-g -O2 -funswitch-loops -floop-flatten -DIN_GCC -fno-common  -DHAVE_CONFIG_H
-I. -I. -I/home/matt/src/gcc-4.7.0/gcc -I/home/matt/src/gcc-4.7.0/gcc/.
-I/home/matt/src/gcc-4.7.0/gcc/../include
-I/home/matt/src/gcc-4.7.0/gcc/../libcpp/include 
-I/home/matt/src/gcc-4.7.0/gcc/../libdecnumber
-I/home/matt/src/gcc-4.7.0/gcc/../libdecnumber/bid -I../libdecnumber   
/home/matt/src/gcc-4.7.0/gcc/caller-save.c -o caller-save.o


/home/matt/src/gcc-4.7.0/gcc/caller-save.c: In function ‘void
init_save_areas()’:
/home/matt/src/gcc-4.7.0/gcc/caller-save.c:292:1: internal compiler error: in
psct_dynamic_dim, at graphite-poly.h:659


This one does produce some potentially relevant valgrind output:

==5057== Conditional jump or move depends on uninitialised value(s)
==5057==    at 0x9E46B6:
_ZL24call_may_clobber_ref_p_1P18gimple_statement_dP8ao_ref_s.951695.39962
(tree-ssa-alias.c:1494)
==5057==    by 0x9E506E: stmt_may_clobber_ref_p_1(gimple_statement_d*,
ao_ref_s*) (tree-ssa-alias.c:1753)
==5057==    by 0x9E51F9:
_ZL20walk_aliased_vdefs_1P8ao_ref_sP9tree_nodePFbS0_S2_PvES3_PP15bitmap_head_defj.951731.constprop.2807.35016
(tree-ssa-alias.c:2158)
==5057==    by 0x9E53D6: walk_aliased_vdefs(ao_ref_s*, tree_node*, bool
(*)(ao_ref_s*, tree_node*, void*), void*, bitmap_head_def**)
(tree-ssa-alias.c:2178)
==5057==    by 0xD6E9F4:
_ZL20detect_type_change_1P9tree_nodeS0_S0_P18gimple_statement_dP13ipa_jump_funcl.496274.33562
(ipa-prop.c:460)
==5057==    by 0xD6F90B:
_ZL35ipa_compute_jump_functions_for_edgeP19param_analysis_infoP11cgraph_edge.496762.33448
(ipa-prop.c:922)
==5057==    by 0xD70591: ipa_analyze_node(cgraph_node*) (ipa-prop.c:1203)
==5057==    by 0xD70CEC: _ZL21ipcp_generate_summaryv.1440941 (ipa-cp.c:2498)
==5057==    by 0xD99B92: execute_ipa_summary_passes(ipa_opt_pass_d*)
(passes.c:1957)
==5057==    by 0xE87E94: cgraph_optimize() (cgraphunit.c:2059)
==5057==    by 0xE889D9: cgraph_finalize_compilation_unit() (cgraphunit.c:1327)
==5057==    by 0xE89046: cp_write_global_declarations() (decl2.c:4050)
==5057== 
==5057== Conditional jump or move depends on uninitialised value(s)
==5057==    at 0x9DF9DE: refs_may_alias_p_1(ao_ref_s*, ao_ref_s*, bool)
(tree-ssa-alias.c:1027)
==5057==    by 0x9E5026: stmt_may_clobber_ref_p_1(gimple_statement_d*,
ao_ref_s*) (tree-ssa-alias.c:1762)
==5057==    by 0x9E51F9:
_ZL20walk_aliased_vdefs_1P8ao_ref_sP9tree_nodePFbS0_S2_PvES3_PP15bitmap_head_defj.951731.constprop.2807.35016
(tree-ssa-alias.c:2158)
==5057==    by 0x9E53D6: walk_aliased_vdefs(ao_ref_s*, tree_node*, bool
(*)(ao_ref_s*, tree_node*, void*), void*, bitmap_head_def**)
(tree-ssa-alias.c:2178)
==5057==    by 0xD6E9F4:
_ZL20detect_type_change_1P9tree_nodeS0_S0_P18gimple_statement_dP13ipa_jump_funcl.496274.33562
(ipa-prop.c:460)
==5057==    by 0xD6F90B:
_ZL35ipa_compute_jump_functions_for_edgeP19param_analysis_infoP11cgraph_edge.496762.33448
(ipa-prop.c:922)
==5057==    by 0xD70591: ipa_analyze_node(cgraph_node*) (ipa-prop.c:1203)
==5057==    by 0xD70CEC: _ZL21ipcp_generate_summaryv.1440941 (ipa-cp.c:2498)
==5057==    by 0xD99B92: execute_ipa_summary_passes(ipa_opt_pass_d*)
(passes.c:1957)
==5057==    by 0xE87E94: cgraph_optimize() (cgraphunit.c:2059)
==5057==    by 0xE889D9: cgraph_finalize_compilation_unit() (cgraphunit.c:1327)
==5057==    by 0xE89046: cp_write_global_declarations() (decl2.c:4050)

[Bug middle-end/51769] bootstrap fails when using -O2 -funswitch-loops -floop-flatten

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51769

--- Comment #1 from Matt Hargett <matt at use dot net> 2012-01-05 16:03:06 UTC ---
Created attachment 26255
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26255
pre-processed source of the file that triggers the ICE

commandline to trigger the ICE with the attached file (once decompressed):
g++ -O2 -funswitch-loops -floop-flatten -c caller-save.i

Removing any one of the options, or replacing the O2 with Os, eliminated the
ICE.