From e7fbaebc8ff650df76f43e92cb9ca59d5174ebe7 Mon Sep 17 00:00:00 2001 From: hjl Date: Thu, 15 Mar 2018 17:54:40 +0000 Subject: [PATCH 13/13] i386: Don't generate alias for function return thunk Function return thunks shouldn't be aliased to indirect branch thunks since indirect branch thunks are placed in COMDAT section and a COMDAT section with indirect branch may not have function return thunk. This patch generates function return thunks directly. gcc/ Backport from mainline PR target/84574 * config/i386/i386.c (indirect_thunk_needed): Update comments. (indirect_thunk_bnd_needed): Likewise. (indirect_thunks_used): Likewise. (indirect_thunks_bnd_used): Likewise. (indirect_return_needed): New. (indirect_return_bnd_needed): Likewise. (output_indirect_thunk_function): Add a bool argument for function return. (output_indirect_thunk_function): Don't generate alias for function return thunk. (ix86_code_end): Call output_indirect_thunk_function to generate function return thunks. (ix86_output_function_return): Set indirect_return_bnd_needed and indirect_return_needed instead of indirect_thunk_bnd_needed and indirect_thunk_needed. gcc/testsuite/ Backport from mainline PR target/84574 * gcc.target/i386/ret-thunk-9.c: Expect __x86_return_thunk label instead of __x86_indirect_thunk label. --- gcc/config/i386/i386.c | 92 ++++++++++------------------- gcc/testsuite/gcc.target/i386/ret-thunk-9.c | 2 +- 2 files changed, 33 insertions(+), 61 deletions(-) diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 21c3c18bd3c..f4cd1c6f4e9 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -11067,19 +11067,23 @@ ix86_setup_frame_addresses (void) labels in call and return thunks. */ static int indirectlabelno; -/* True if call and return thunk functions are needed. */ +/* True if call thunk function is needed. */ static bool indirect_thunk_needed = false; -/* True if call and return thunk functions with the BND prefix are - needed. */ +/* True if call thunk function with the BND prefix is needed. */ static bool indirect_thunk_bnd_needed = false; /* Bit masks of integer registers, which contain branch target, used - by call and return thunks functions. */ + by call thunk functions. */ static int indirect_thunks_used; /* Bit masks of integer registers, which contain branch target, used - by call and return thunks functions with the BND prefix. */ + by call thunk functions with the BND prefix. */ static int indirect_thunks_bnd_used; +/* True if return thunk function is needed. */ +static bool indirect_return_needed = false; +/* True if return thunk function with the BND prefix is needed. */ +static bool indirect_return_bnd_needed = false; + /* True if return thunk function via CX is needed. */ static bool indirect_return_via_cx; /* True if return thunk function via CX with the BND prefix is @@ -11226,16 +11230,18 @@ output_indirect_thunk (bool need_bnd_p, unsigned int regno) /* Output a funtion with a call and return thunk for indirect branch. If BND_P is true, the BND prefix is needed. If REGNO != INVALID_REGNUM, the function address is in REGNO. Otherwise, the function address is - on the top of stack. */ + on the top of stack. Thunk is used for function return if RET_P is + true. */ static void -output_indirect_thunk_function (bool need_bnd_p, unsigned int regno) +output_indirect_thunk_function (bool need_bnd_p, unsigned int regno, + bool ret_p) { char name[32]; tree decl; /* Create __x86_indirect_thunk/__x86_indirect_thunk_bnd. */ - indirect_thunk_name (name, regno, need_bnd_p, false); + indirect_thunk_name (name, regno, need_bnd_p, ret_p); decl = build_decl (BUILTINS_LOCATION, FUNCTION_DECL, get_identifier (name), build_function_type_list (void_type_node, NULL_TREE)); @@ -11278,50 +11284,6 @@ output_indirect_thunk_function (bool need_bnd_p, unsigned int regno) ASM_OUTPUT_LABEL (asm_out_file, name); } - /* Create alias for __x86_return_thunk/__x86_return_thunk_bnd or - __x86_return_thunk_ecx/__x86_return_thunk_ecx_bnd. */ - bool need_alias; - if (regno == INVALID_REGNUM) - need_alias = true; - else if (regno == CX_REG) - { - if (need_bnd_p) - need_alias = indirect_return_via_cx_bnd; - else - need_alias = indirect_return_via_cx; - } - else - need_alias = false; - - if (need_alias) - { - char alias[32]; - - indirect_thunk_name (alias, regno, need_bnd_p, true); -#if TARGET_MACHO - if (TARGET_MACHO) - { - fputs ("\t.weak_definition\t", asm_out_file); - assemble_name (asm_out_file, alias); - fputs ("\n\t.private_extern\t", asm_out_file); - assemble_name (asm_out_file, alias); - putc ('\n', asm_out_file); - ASM_OUTPUT_LABEL (asm_out_file, alias); - } -#else - ASM_OUTPUT_DEF (asm_out_file, alias, name); - if (USE_HIDDEN_LINKONCE) - { - fputs ("\t.globl\t", asm_out_file); - assemble_name (asm_out_file, alias); - putc ('\n', asm_out_file); - fputs ("\t.hidden\t", asm_out_file); - assemble_name (asm_out_file, alias); - putc ('\n', asm_out_file); - } -#endif - } - DECL_INITIAL (decl) = make_node (BLOCK); current_function_decl = decl; allocate_struct_function (decl, false); @@ -11368,19 +11330,29 @@ ix86_code_end (void) rtx xops[2]; unsigned int regno; + if (indirect_return_needed) + output_indirect_thunk_function (false, INVALID_REGNUM, true); + if (indirect_return_bnd_needed) + output_indirect_thunk_function (true, INVALID_REGNUM, true); + + if (indirect_return_via_cx) + output_indirect_thunk_function (false, CX_REG, true); + if (indirect_return_via_cx_bnd) + output_indirect_thunk_function (true, CX_REG, true); + if (indirect_thunk_needed) - output_indirect_thunk_function (false, INVALID_REGNUM); + output_indirect_thunk_function (false, INVALID_REGNUM, false); if (indirect_thunk_bnd_needed) - output_indirect_thunk_function (true, INVALID_REGNUM); + output_indirect_thunk_function (true, INVALID_REGNUM, false); for (regno = FIRST_REX_INT_REG; regno <= LAST_REX_INT_REG; regno++) { unsigned int i = regno - FIRST_REX_INT_REG + LAST_INT_REG + 1; if ((indirect_thunks_used & (1 << i))) - output_indirect_thunk_function (false, regno); + output_indirect_thunk_function (false, regno, false); if ((indirect_thunks_bnd_used & (1 << i))) - output_indirect_thunk_function (true, regno); + output_indirect_thunk_function (true, regno, false); } for (regno = AX_REG; regno <= SP_REG; regno++) @@ -11389,10 +11361,10 @@ ix86_code_end (void) tree decl; if ((indirect_thunks_used & (1 << regno))) - output_indirect_thunk_function (false, regno); + output_indirect_thunk_function (false, regno, false); if ((indirect_thunks_bnd_used & (1 << regno))) - output_indirect_thunk_function (true, regno); + output_indirect_thunk_function (true, regno, false); if (!(pic_labels_used & (1 << regno))) continue; @@ -28077,12 +28049,12 @@ ix86_output_function_return (bool long_p) true); if (need_bnd_p) { - indirect_thunk_bnd_needed |= need_thunk; + indirect_return_bnd_needed |= need_thunk; fprintf (asm_out_file, "\tbnd jmp\t%s\n", thunk_name); } else { - indirect_thunk_needed |= need_thunk; + indirect_return_needed |= need_thunk; fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name); } } diff --git a/gcc/testsuite/gcc.target/i386/ret-thunk-9.c b/gcc/testsuite/gcc.target/i386/ret-thunk-9.c index d2df8b874e0..eee230ca2f6 100644 --- a/gcc/testsuite/gcc.target/i386/ret-thunk-9.c +++ b/gcc/testsuite/gcc.target/i386/ret-thunk-9.c @@ -13,7 +13,7 @@ foo (void) /* { dg-final { scan-assembler "jmp\[ \t\]*__x86_return_thunk" } } */ /* { dg-final { scan-assembler "jmp\[ \t\]*\.LIND" } } */ /* { dg-final { scan-assembler "call\[ \t\]*\.LIND" } } */ -/* { dg-final { scan-assembler "__x86_indirect_thunk:" } } */ +/* { dg-final { scan-assembler "__x86_return_thunk:" } } */ /* { dg-final { scan-assembler "mov(?:l|q)\[ \t\]*_?bar" { target *-*-linux* } } } */ /* { dg-final { scan-assembler-times {\tpause} 2 } } */ /* { dg-final { scan-assembler-times {\tlfence} 2 } } */ -- 2.16.3