Hi Jiong, On 02/06/16 15:44, Jiong Wang wrote:
On 31/05/16 15:15, Kyrill Tkachov wrote:+/* Compute the atrribute "length" of insn. Currently, this function is used + for "*load_multiple_with_writeback", "*pop_multiple_with_return" and + "*pop_multiple_with_writeback_and_return". */ + s/atrribute/attribute/ Also, please add a description of the function arguments to the function comment. +int +arm_attr_length_pop_multi(rtx *operands, bool return_pc, bool write_back_p) +{ space between function name and '('. + /* ARM mode. */ + if (TARGET_ARM) + return 4; + /* Thumb1 mode. */ + if (TARGET_THUMB1) + return 2; + + /* For POP/PUSH/LDM/STM under Thumb2 mode, we can use 16-bit Thumb encodings + if the register list is 8-bit. Normally this means all registers in the + list must be LO_REGS, that is (R0 -R7). If any HI_REGS used, then we must + use 32-bit encodings. But there are two exceptions to this rule where + special HI_REGS used in PUSH/POP. + + 1. 16-bit Thumb encoding POP can use an 8-bit register list, and an + additional bit, P, that corresponds to the PC. This means it can access + any of {PC, R7-R0}. It took me a bit to figure it out but this bit 'P' you're talking about is a just a bit in the illustration in the ARM Architecture Reference Manual (section A8.8.131). I don't think it's useful to refer to it. This would be better phrased as "The encoding is 16 bits wide if the register list contains only the registers in {R0 - R7} or the PC". + 2. 16-bit Thumb encoding PUSH can use an 8-bit register list, and an + additional bit, M , that corresponds to the LR. This means it can + access any of {LR, R7-R0}. */ + This function only deals with POP instructions, so talking about PUSH encodings is confusing. I suggest you drop point 2).Thanks, all fixed. Meanwhile I splitted the comments to keep PUSH part in arm_attr_length_push_multi. Patch updated. OK for trunk? gcc/ 2016-06-02 Jiong Wang <jiong.w...@arm.com> PR target/71061 * config/arm/arm-protos.h (arm_attr_length_pop_multi): New declaration. * config/arm/arm.c (arm_attr_length_pop_multi): New function to return length for pop patterns. (arm_attr_length_push_multi): Update comments. * config/arm/arm.md (*load_multiple_with_writeback): Set "length" attribute. (*pop_multiple_with_writeback_and_return): Likewise. (*pop_multiple_with_return): Likewise.
Ok if bootstrap and test with --with-mode=thumb is successful. Thanks, Kyrill
