The attached patch fixes the stack layout problems on AIX and Power as described here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77359 The patch has been bootstrapped on AIX (32 Bit) and bootstrappend and regression tested on Power (biarch). It needs more testing that I cannot do with the hardware available to me. If the patch is good, this one can be re-applied: https://gcc.gnu.org/ml/gcc-patches/2016-07/msg01730.html https://gcc.gnu.org/ml/gcc-patches/2016-08/msg01616.html Ciao Dominik ^_^ ^_^ -- Dominik Vogt IBM Germany
gcc/ChangeLog * config/rs6000/rs6000.c (rs6000_stack_info): Properly align local variables in functions calling alloca. * config/rs6000/rs6000.h (STARTING_FRAME_OFFSET, STACK_DYNAMIC_OFFSET): Likewise. * config/rs6000/aix.h (STARTING_FRAME_OFFSET, STACK_DYNAMIC_OFFSET): Copy AIX specific versions of the rs6000.h macros to aix.h.
>From bd36042fd82e29204d2f10c180b9e7c27281eef2 Mon Sep 17 00:00:00 2001 From: Dominik Vogt <v...@linux.vnet.ibm.com> Date: Fri, 28 Oct 2016 12:59:55 +0100 Subject: [PATCH] PR77359: Properly align local variables in functions calling alloca. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77359 for a discussion of the problem and the fix. --- gcc/config/rs6000/aix.h | 27 +++++++++++++++++++++++++++ gcc/config/rs6000/rs6000.c | 9 +++++++-- gcc/config/rs6000/rs6000.h | 14 ++++++++------ 3 files changed, 42 insertions(+), 8 deletions(-) diff --git a/gcc/config/rs6000/aix.h b/gcc/config/rs6000/aix.h index b254236..7773517 100644 --- a/gcc/config/rs6000/aix.h +++ b/gcc/config/rs6000/aix.h @@ -40,6 +40,33 @@ #undef STACK_BOUNDARY #define STACK_BOUNDARY 128 +/* Offset within stack frame to start allocating local variables at. + If FRAME_GROWS_DOWNWARD, this is the offset to the END of the + first local allocated. Otherwise, it is the offset to the BEGINNING + of the first local allocated. + + On the RS/6000, the frame pointer is the same as the stack pointer, + except for dynamic allocations. So we start after the fixed area and + outgoing parameter area. */ + +#undef STARTING_FRAME_OFFSET +#define STARTING_FRAME_OFFSET \ + (FRAME_GROWS_DOWNWARD \ + ? 0 \ + : (cfun->calls_alloca \ + ? RS6000_ALIGN (crtl->outgoing_args_size + RS6000_SAVE_AREA, 16) \ + : (RS6000_ALIGN (crtl->outgoing_args_size, 16) + RS6000_SAVE_AREA))) + +/* Offset from the stack pointer register to an item dynamically + allocated on the stack, e.g., by `alloca'. + + The default value for this macro is `STACK_POINTER_OFFSET' plus the + length of the outgoing arguments. The default is correct for most + machines. See `function.c' for details. */ +#undef STACK_DYNAMIC_OFFSET +#define STACK_DYNAMIC_OFFSET(FUNDECL) \ + RS6000_ALIGN (crtl->outgoing_args_size + (STACK_POINTER_OFFSET), 16) + #undef TARGET_IEEEQUAD #define TARGET_IEEEQUAD 0 diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index f9e4739..02ed9c1 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -26004,8 +26004,13 @@ rs6000_stack_info (void) info->reg_size = reg_size; info->fixed_size = RS6000_SAVE_AREA; info->vars_size = RS6000_ALIGN (get_frame_size (), 8); - info->parm_size = RS6000_ALIGN (crtl->outgoing_args_size, - TARGET_ALTIVEC ? 16 : 8); + if (cfun->calls_alloca) + info->parm_size = + RS6000_ALIGN (crtl->outgoing_args_size + info->fixed_size, + STACK_BOUNDARY / BITS_PER_UNIT) - info->fixed_size; + else + info->parm_size = RS6000_ALIGN (crtl->outgoing_args_size, + TARGET_ALTIVEC ? 16 : 8); if (FRAME_GROWS_DOWNWARD) info->vars_size += RS6000_ALIGN (info->fixed_size + info->vars_size + info->parm_size, diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h index 4b83abd..c11dc1b 100644 --- a/gcc/config/rs6000/rs6000.h +++ b/gcc/config/rs6000/rs6000.h @@ -1728,9 +1728,12 @@ extern enum reg_class rs6000_constraints[RS6000_CONSTRAINT_MAX]; #define STARTING_FRAME_OFFSET \ (FRAME_GROWS_DOWNWARD \ ? 0 \ - : (RS6000_ALIGN (crtl->outgoing_args_size, \ - (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8) \ - + RS6000_SAVE_AREA)) + : (cfun->calls_alloca \ + ? (RS6000_ALIGN (crtl->outgoing_args_size + RS6000_SAVE_AREA, \ + (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8 )) \ + : (RS6000_ALIGN (crtl->outgoing_args_size, \ + (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8) \ + + RS6000_SAVE_AREA))) /* Offset from the stack pointer register to an item dynamically allocated on the stack, e.g., by `alloca'. @@ -1739,9 +1742,8 @@ extern enum reg_class rs6000_constraints[RS6000_CONSTRAINT_MAX]; length of the outgoing arguments. The default is correct for most machines. See `function.c' for details. */ #define STACK_DYNAMIC_OFFSET(FUNDECL) \ - (RS6000_ALIGN (crtl->outgoing_args_size, \ - (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8) \ - + (STACK_POINTER_OFFSET)) + RS6000_ALIGN (crtl->outgoing_args_size + (STACK_POINTER_OFFSET), \ + (TARGET_ALTIVEC || TARGET_VSX) ? 16 : 8) /* If we generate an insn to push BYTES bytes, this says how many the stack pointer really advances by. -- 2.3.0