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[PATCH, RTX]: Additional fix for PR 57003

From: Uros Bizjak <ubizjak at gmail dot com>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: Jakub Jelinek <jakub at redhat dot com>
Date: Fri, 3 Oct 2014 19:54:01 +0200
Subject: [PATCH, RTX]: Additional fix for PR 57003
Authentication-results: sourceware.org; auth=none

Hello!

My r215428 change exposed another PR 57003 problem on x86_64. When
compiling gcc.target/i386/pr57003.c we refer to clobbered %rdi
register after the call to memcpy:

--- pr57003.s   2014-10-03 15:08:24.000000000 +0200
+++ pr57003_.s  2014-10-03 15:08:19.000000000 +0200
@@ -78,7 +78,7 @@
        leaq    -20(%rbx), %rdx
        movq    %rax, %rdi
        call    memcpy
-       movq    %rdi, c(%rip)
+       movq    %rax, c(%rip)
 .L8:
        movaps  (%rsp), %xmm6
        movaps  16(%rsp), %xmm7
@@ -321,5 +321,5 @@
        .byte   0xb
        .align 8
 .LEFDE7:
-       .ident  "GCC: (GNU) 5.0.0 20141002 (experimental) [trunk
revision 215797]"
+       .ident  "GCC: (GNU) 4.9.2 20141001 (prerelease)
[gcc-4_9-branch revision 215749]"
        .section        .note.GNU-stack,"",@progbits

The runtime failure happens only on CentOS5 (and not in Fedora20),
which supports findings in Comment #17 of the PR.

The difference is, that now we emit memcpy for MS_ABI->ELF_ABI
cross-ABI call as:

#(call_insn:TI 24 23 27 3 (set (reg:DI 0 ax)
#        (call (mem:QI (symbol_ref:DI ("memcpy") [flags 0x41]
<function_decl 0x7fce6f586438 memcpy>) [0 memcpy S1 A8])
#            (const_int 0 [0]))) pr57003.c:32 661 {*call_value}
#     (expr_list:REG_DEAD (reg:DI 5 di)
#        (expr_list:REG_DEAD (reg:DI 4 si)
#            (expr_list:REG_DEAD (reg:DI 1 dx)
#                (expr_list:REG_UNUSED (reg:DI 0 ax)
#                    (expr_list:REG_RETURNED (reg/v/f:DI 2 cx [orig:87 e ] [87])
#                        (expr_list:REG_CALL_DECL (symbol_ref:DI
("memcpy") [flags 0x41] <function_decl 0x7fce6f586438 memcpy>)
#                            (expr_list:REG_EH_REGION (const_int 0 [0])
#                                (nil))))))))
#    (expr_list (clobber (reg:TI 52 xmm15))
#        (expr_list (clobber (reg:TI 51 xmm14))
#            (expr_list (clobber (reg:TI 50 xmm13))
#                (expr_list (clobber (reg:TI 49 xmm12))
#                    (expr_list (clobber (reg:TI 48 xmm11))
#                        (expr_list (clobber (reg:TI 47 xmm10))
#                            (expr_list (clobber (reg:TI 46 xmm9))
#                                (expr_list (clobber (reg:TI 45 xmm8))
#                                    (expr_list (clobber (reg:TI 28 xmm7))
#                                        (expr_list (clobber (reg:TI 27 xmm6))
#                                            (expr_list (clobber (reg:DI 5 di))
#                                                (expr_list (clobber
(reg:DI 4 si))
#                                                    (expr_list:DI
(set (reg:DI 0 ax)
#                                                            (reg:DI 5 di))
#                                                        (expr_list:DI
(use (reg:DI 5 di))
#
(expr_list:DI (use (reg:DI 4 si))
#
(expr_list:DI (use (reg:DI 1 dx))
#
(nil))))))))))))))))))

which is alternate, but equivalent form of what was generated previously:

#(call_insn:TI 24 23 27 3 (parallel [
#            (set (reg:DI 0 ax)
#                (call (mem:QI (symbol_ref:DI ("memcpy") [flags 0x41]
<function_decl 0x7fd91824a800 memcpy>) [0 memcpy S1 A8])
#                    (const_int 0 [0])))
#            (unspec [
#                    (const_int 0 [0])
#                ] UNSPEC_MS_TO_SYSV_CALL)
#            (clobber (reg:DI 4 si))
#            (clobber (reg:DI 5 di))
#            (clobber (reg:TI 27 xmm6))
#            (clobber (reg:TI 28 xmm7))
#            (clobber (reg:TI 45 xmm8))
#            (clobber (reg:TI 46 xmm9))
#            (clobber (reg:TI 47 xmm10))
#            (clobber (reg:TI 48 xmm11))
#            (clobber (reg:TI 49 xmm12))
#            (clobber (reg:TI 50 xmm13))
#            (clobber (reg:TI 51 xmm14))
#            (clobber (reg:TI 52 xmm15))
#        ]) pr57003.c:32 652 {*call_value_rex64_ms_sysv}
#     (expr_list:REG_DEAD (reg:DI 5 di)
#        (expr_list:REG_DEAD (reg:DI 4 si)
#            (expr_list:REG_DEAD (reg:DI 1 dx)
#                (expr_list:REG_RETURNED (reg/v/f:DI 2 cx [orig:87 e ] [87])
#                    (expr_list:REG_EH_REGION (const_int 0 [0])
#                        (nil))))))
#    (expr_list:DI (set (reg:DI 0 ax)
#            (reg:DI 5 di))
#        (expr_list:DI (use (reg:DI 5 di))
#            (expr_list:DI (use (reg:DI 4 si))
#                (expr_list:DI (use (reg:DI 1 dx))
#                    (nil))))))

It looks that Jakub's patch, proposed in Comment #21 doesn't cover
alternative form, so it doesn't record clobbers properly.

Attached patch fixes this omission.

2014-10-03  Uros Bizjak  <ubizjak@gmail.com>

    PR rtl-optimization/57003
    * regcprop.c (copyprop_hardreg_forward_1): If ksvd.ignore_set_reg,
    also check CALL_INSN_FUNCTION_USAGE for clobbers again after
    killing regs_invalidated_by_call.

Tested on x86_64-linux-gnu {,-m32}.

OK for mainline and release branches?

Uros.

Attachment: p.diff.txt
Description: Text document

Follow-Ups:
- Re: [PATCH, RTX]: Additional fix for PR 57003
  - From: Jeff Law

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