Skip to content
This repository has been archived by the owner on Sep 2, 2023. It is now read-only.

Transform loops to reverse iteration #18

Open
mbitsnbites opened this issue Feb 12, 2020 · 1 comment
Open

Transform loops to reverse iteration #18

mbitsnbites opened this issue Feb 12, 2020 · 1 comment

Comments

@mbitsnbites
Copy link
Member

Most MRISC32 branch instructions like to compare against zero. If loops go from N downto zero, we can skip one compare instruction.

Caveat: May require an extra index register/increment?
@mbitsnbites
Copy link
Member Author

See decrement_and_branch_until_zero and http://www.chiark.greenend.org.uk/doc/gcc-4.3-doc/gccint.html#Looping-Patterns

mbitsnbites pushed a commit that referenced this issue Sep 6, 2020
arm: Improve immediate generation for thumb-1 with -mpurecode [PR96769]
2033a63 
This patch moves the move-immediate splitter after the regular ones so
that it has lower precedence, and updates its constraints.

For
int f3 (void) { return 0x11000000; }
int f3_2 (void) { return 0x12345678; }

we now generate:
* with -O2 -mcpu=cortex-m0 -mpure-code:
f3:
	movs    r0, #136
	lsls    r0, r0, #21
	bx      lr
f3_2:
	movs    r0, #18
	lsls    r0, r0, #8
	adds    r0, r0, gcc-mirror#52
	lsls    r0, r0, #8
	adds    r0, r0, gcc-mirror#86
	lsls    r0, r0, #8
	adds    r0, r0, #121
	bx      lr

* with -O2 -mcpu=cortex-m23 -mpure-code:
f3:
	movs    r0, #136
	lsls    r0, r0, #21
	bx      lr
f3_2:
	movw    r0, #22136
	movt    r0, 4660
	bx      lr

2020-09-04  Christophe Lyon  <[email protected]>

	PR target/96769
	gcc/
	* config/arm/thumb1.md: Move movsi splitter for
	arm_disable_literal_pool after the other movsi splitters.

	gcc/testsuite/
	* gcc.target/arm/pure-code/pr96769.c: New test.
mbitsnbites pushed a commit that referenced this issue Oct 18, 2020
@marxin
IPA: prevent an UBSAN error
ab87b0a 
Prevents the following UBSAN error:

./xgcc -B. /home/marxin/Programming/gcc/gcc/testsuite/g++.dg/torture/pr49770.C -O2 -c
/home/marxin/Programming/gcc2/gcc/ipa-modref-tree.h:482:22: runtime error: load of value 2, which is not a valid value for type 'bool'
    #0 0x1fdb4d1 in modref_tree<int>::merge(modref_tree<int>*, vec<modref_parm_map, va_heap, vl_ptr>*) /home/marxin/Programming/gcc2/gcc/ipa-modref-tree.h:482
    #1 0x1fcadaa in merge_call_side_effects(modref_summary*, gimple*, modref_summary*, bool) /home/marxin/Programming/gcc2/gcc/ipa-modref.c:511
    #2 0x1fcbadd in analyze_call /home/marxin/Programming/gcc2/gcc/ipa-modref.c:642
    #3 0x1fcc061 in analyze_stmt /home/marxin/Programming/gcc2/gcc/ipa-modref.c:732
    #4 0x1fccf31 in analyze_function /home/marxin/Programming/gcc2/gcc/ipa-modref.c:823
    #5 0x1fd17e5 in execute /home/marxin/Programming/gcc2/gcc/ipa-modref.c:1441
    #6 0x25cca6e in execute_one_pass(opt_pass*) /home/marxin/Programming/gcc2/gcc/passes.c:2509
    #7 0x25cd39b in execute_pass_list_1 /home/marxin/Programming/gcc2/gcc/passes.c:2597
    #8 0x25cd450 in execute_pass_list_1 /home/marxin/Programming/gcc2/gcc/passes.c:2598
    #9 0x25cd4ee in execute_pass_list(function*, opt_pass*) /home/marxin/Programming/gcc2/gcc/passes.c:2608
    #10 0x25c7a5a in do_per_function_toporder(void (*)(function*, void*), void*) /home/marxin/Programming/gcc2/gcc/passes.c:1726
    #11 0x25cfa3f in execute_ipa_pass_list(opt_pass*) /home/marxin/Programming/gcc2/gcc/passes.c:2941
    #12 0x173572d in ipa_passes /home/marxin/Programming/gcc2/gcc/cgraphunit.c:2642
    #13 0x17364ee in symbol_table::compile() /home/marxin/Programming/gcc2/gcc/cgraphunit.c:2777
    #14 0x17372d9 in symbol_table::finalize_compilation_unit() /home/marxin/Programming/gcc2/gcc/cgraphunit.c:3022
    #15 0x2a1f00a in compile_file /home/marxin/Programming/gcc2/gcc/toplev.c:485
    #16 0x2a27dc8 in do_compile /home/marxin/Programming/gcc2/gcc/toplev.c:2321
    #17 0x2a283cc in toplev::main(int, char**) /home/marxin/Programming/gcc2/gcc/toplev.c:2460
    #18 0x54f21cd in main /home/marxin/Programming/gcc2/gcc/main.c:39
    #19 0x7ffff6f0de09 in __libc_start_main ../csu/libc-start.c:314
    #20 0x9eac09 in _start (/home/marxin/Programming/gcc2/objdir/gcc/cc1plus+0x9eac09)

gcc/ChangeLog:

	* ipa-modref.c (merge_call_side_effects): Clear modref_parm_map
	fields in the vector.
mbitsnbites pushed a commit that referenced this issue Jun 26, 2021
@marxin
evrp: fix AddressSanitizer: alloc-dealloc-mismatch
44b1502 
The fixed error is:

==21166==ERROR: AddressSanitizer: alloc-dealloc-mismatch (operator new [] vs operator delete) on 0x60300000d900
    #0 0x7367d7 in operator delete(void*, unsigned long) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/libsanitizer/asan/asan_new_delete.cpp:172
    #1 0x3b82e6e in pointer_equiv_analyzer::~pointer_equiv_analyzer() /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/gimple-ssa-evrp.c:161
    #2 0x3b83387 in hybrid_folder::~hybrid_folder() /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/gimple-ssa-evrp.c:517
    #3 0x3b83387 in execute_early_vrp /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/gimple-ssa-evrp.c:686
    #4 0x1790611 in execute_one_pass(opt_pass*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:2567
    #5 0x1792003 in execute_pass_list_1 /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:2656
    #6 0x1792029 in execute_pass_list_1 /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:2657
    #7 0x179209f in execute_pass_list(function*, opt_pass*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:2667
    #8 0x178a5f3 in do_per_function_toporder(void (*)(function*, void*), void*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:1773
    #9 0x1792fac in do_per_function_toporder(void (*)(function*, void*), void*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/plugin.h:191
    #10 0x1792fac in execute_ipa_pass_list(opt_pass*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/passes.c:3001
    #11 0xc525fc in ipa_passes /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/cgraphunit.c:2154
    #12 0xc525fc in symbol_table::compile() /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/cgraphunit.c:2289
    #13 0xc5a096 in symbol_table::compile() /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/cgraphunit.c:2269
    #14 0xc5a096 in symbol_table::finalize_compilation_unit() /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/cgraphunit.c:2537
    #15 0x1a7a17c in compile_file /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/toplev.c:482
    #16 0x69c758 in do_compile /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/toplev.c:2210
    #17 0x69c758 in toplev::main(int, char**) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/toplev.c:2349
    #18 0x6a932a in main /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/main.c:39
    #19 0x7ffff7820b34 in __libc_start_main ../csu/libc-start.c:332
    #20 0x6aa5fd in _start (/home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/objdir/gcc/cc1+0x6aa5fd)

0x60300000d900 is located 0 bytes inside of 32-byte region [0x60300000d900,0x60300000d920)
allocated by thread T0 here:
    #0 0x735ab7 in operator new[](unsigned long) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/libsanitizer/asan/asan_new_delete.cpp:102
    #1 0x3b82dac in pointer_equiv_analyzer::pointer_equiv_analyzer(gimple_ranger*) /home/marxin/BIG/buildbot/buildworker/marxinbox-gcc-asan/build/gcc/gimple-ssa-evrp.c:156

gcc/ChangeLog:

	* gimple-ssa-evrp.c (pointer_equiv_analyzer::~pointer_equiv_analyzer): Use delete[].
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
1 participant
@mbitsnbites