From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20915 invoked by alias); 25 Jun 2004 12:01:32 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 20622 invoked by uid 48); 25 Jun 2004 12:01:16 -0000 Date: Fri, 25 Jun 2004 12:25:00 -0000 Message-ID: <20040625120116.20621.qmail@sourceware.org> From: "jakub at gcc dot gnu dot org" To: gcc-bugs@gcc.gnu.org In-Reply-To: <20040625110154.16195.jakub@gcc.gnu.org> References: <20040625110154.16195.jakub@gcc.gnu.org> Reply-To: gcc-bugzilla@gcc.gnu.org Subject: [Bug target/16195] Miscompilation of GCC 3.3.x by 3.4.x X-Bugzilla-Reason: CC X-SW-Source: 2004-06/txt/msg03153.txt.bz2 List-Id: ------- Additional Comments From jakub at gcc dot gnu dot org 2004-06-25 12:01 ------- At lreg time there is: (insn 38 66 39 3 (set (reg:DF 127 [ x ]) (mem/u/f:DF (plus:DI (reg:DI 30 30) (const:DI (minus:DI (symbol_ref/u:DI ("*.LC1") [flags 0x2]) (symbol_ref:DI ("*.LCTOC1"))))) [0 S8 A64])) 312 {*movdf_hardfloat64} (nil) (expr_list:REG_DEAD (reg:DI 30 30) (expr_list:REG_EQUAL (const_double:DF 7.0e+1 [0x0.8cp+7]) (nil)))) ... (insn 40 67 42 4 (set (mem/f:DF (plus:DI (reg/f:DI 31 31) (const_int 112 [0x70])) [0 x+0 S8 A64]) (reg:DF 127 [ x ])) 312 {*movdf_hardfloat64} (nil) (expr_list:REG_DEAD (reg:DF 127 [ x ]) (nil))) ... (insn 43 42 44 4 (set (reg:DF 132) (const_double:DF 3.0e+1 [0x0.fp+5])) 312 {*movdf_hardfloat64} (nil) (nil)) As insn 38 is the last one which uses the PIC register at lreg time, global alloc decides to put DF 127 into DF 30: Reloads for insn # 38 Reload 0: reload_out (DF) = (reg:DF 127 [ x ]) GENERAL_REGS, RELOAD_FOR_OUTPUT (opnum = 0) reload_out_reg: (reg:DF 127 [ x ]) reload_reg_rtx: (reg:DF 30 30) which would be fine if insn 43 was not reloaded into: (insn 43 42 44 4 (set (reg:DF 32 0 [132]) (mem/u/f:DF (plus:DI (reg:DI 30 30) (const:DI (minus:DI (symbol_ref/u:DI ("*.LC3") [flags 0x2]) (symbol_ref:DI ("*.LCTOC1"))))) [0 S8 A64])) 312 {*movdf_hardfloat64} (nil) (nil)) RS6000_PIC_OFFSET_TABLE_REGNUM is not a fixed reg on ppc64 and insn 43 at lreg time has no (use (reg:DI 30 30)) or something similar, so there is nothing that prevents this. In GCC 3.3.4 the situation is the same, but the testcase works, as register f0 is chosen instead of r30. In 3.4 without -mminimal-toc, but with -fpic or -fPIC the situation is very similar, s/r30/r2/, but r0 is chosen instead of r2 and thus the testcase doesn't fail, still I don't see what would prevent under bigger register preasure using that register. Given that rs6000_legitimize_reload_address on TARGET_TOC architectures can reference TOC_REGISTER at any time (call create_TOC_reference ()), I don't see other solution than to: if (TARGET_TOC) { fixed_regs[TOC_REGISTER] = call_used_regs[TOC_REGISTER] = 1; } in CONDITIONAL_REGISTER_USAGE (resp. rs6000_conditional_register_usage in 3.5), do you agree? Dunno if it should be call_really_used_regs[TOC_REGISTER] = 1 as well or not. -- What |Removed |Added ---------------------------------------------------------------------------- CC| |dje at watson dot ibm dot | |com, amodra at bigpond dot | |net dot au http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16195