components/developer/gcc-10/patches/0005-Implement-fstrict-calling-conventions.patch

   1 From 26355d2a256704bb98169455ffa33ffde127384b Mon Sep 17 00:00:00 2001
   2 From: Richard Lowe <richlowe@richlowe.net>
   3 Date: Sat, 27 Oct 2012 02:44:09 +0100
   4 Subject: [PATCH 05/34] Implement -fstrict-calling-conventions
   5
   6 Stock GCC is overly willing to violate the ABI when calling local functions,
   7 such that it passes arguments in registers on i386.  This hampers debugging
   8 with anything other than a fully-aware DWARF debugger, and is generally not
   9 something we desire.
  10
  11 Implement a flag which disables this behaviour, enabled by default.  The flag is
  12 global, though only effective on i386, to more easily allow its globalization
  13 later which, given the odds, is likely to be necessary.
  14 ---
  15  gcc/common.opt                            |  4 ++++
  16  gcc/config/i386/i386.c                    |  2 ++
  17  gcc/doc/invoke.texi                       |  6 ++++++
  18  gcc/testsuite/gcc.target/i386/local.c     |  3 ++-
  19  gcc/testsuite/gcc.target/i386/strict-cc.c | 24 +++++++++++++++++++++++
  20  5 files changed, 38 insertions(+), 1 deletion(-)
  21  create mode 100644 gcc/testsuite/gcc.target/i386/strict-cc.c
  22
  23 diff --git a/gcc/common.opt b/gcc/common.opt
  24 index ec5235c3a41..561e7af9783 100644
  25 --- a/gcc/common.opt
  26 +++ b/gcc/common.opt
  27 @@ -2604,6 +2604,10 @@ fstrict-aliasing
  28  Common Report Var(flag_strict_aliasing) Optimization
  29  Assume strict aliasing rules apply.
  30
  31 +fstrict-calling-conventions
  32 +Common Report Var(flag_strict_calling_conventions) Init(1)
  33 +Use strict ABI calling conventions even for static functions
  34 +
  35  fstrict-overflow
  36  Common Report
  37  Treat signed overflow as undefined.  Negated as -fwrapv -fwrapv-pointer.
  38 diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
  39 index 2f838840e96..6652312b738 100644
  40 --- a/gcc/config/i386/i386.c
  41 +++ b/gcc/config/i386/i386.c
  42 @@ -1117,6 +1117,7 @@ ix86_function_regparm (const_tree type, const_tree decl)
  43          and callee not, or vice versa.  Instead look at whether the callee
  44          is optimized or not.  */
  45        if (target && opt_for_fn (target->decl, optimize)
  46 +         && !flag_strict_calling_conventions
  47           && !(profile_flag && !flag_fentry))
  48         {
  49           if (target->local && target->can_change_signature)
  50 @@ -1213,6 +1214,7 @@ ix86_function_sseregparm (const_tree type, const_tree decl, bool warn)
  51        /* TARGET_SSE_MATH */
  52        && (target_opts_for_fn (target->decl)->x_ix86_fpmath & FPMATH_SSE)
  53        && opt_for_fn (target->decl, optimize)
  54 +      && !flag_strict_calling_conventions
  55        && !(profile_flag && !flag_fentry))
  56      {
  57        if (target->local && target->can_change_signature)
  58 diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
  59 index eabeec944e7..7d863e6a083 100644
  60 --- a/gcc/doc/invoke.texi
  61 +++ b/gcc/doc/invoke.texi
  62 @@ -6290,6 +6290,12 @@ with multiple statement cases using flow-sensitive points-to information.
  63  Only warns when the converted pointer is dereferenced.
  64  Does not warn about incomplete types.
  65
  66 +@item -fstrict-calling-conventions
  67 +@opindex fstrict-calling-conventions
  68 +Use strict ABI calling conventions even with local functions.
  69 +This disable certain optimizations that may cause GCC to call local
  70 +functions in a manner other than that described by the ABI.
  71 +
  72  @item -Wstrict-overflow
  73  @itemx -Wstrict-overflow=@var{n}
  74  @opindex Wstrict-overflow
  75 diff --git a/gcc/testsuite/gcc.target/i386/local.c b/gcc/testsuite/gcc.target/i386/local.c
  76 index f4444951e12..3a487583d81 100644
  77 --- a/gcc/testsuite/gcc.target/i386/local.c
  78 +++ b/gcc/testsuite/gcc.target/i386/local.c
  79 @@ -1,5 +1,6 @@
  80  /* { dg-do compile } */
  81 -/* { dg-options "-O2 -funit-at-a-time" } */
  82 +/* { dg-options "-O2 -funit-at-a-time -fno-strict-calling-conventions" { target ia32 } } */
  83 +/* { dg-options "-O2 -funit-at-a-time" { target lp64 } } */
  84  /* { dg-final { scan-assembler "magic\[^\\n\]*eax" { target ia32 } } } */
  85  /* { dg-final { scan-assembler "magic\[^\\n\]*(edi|ecx)" { target { ! ia32 } } } } */
  86
  87 diff --git a/gcc/testsuite/gcc.target/i386/strict-cc.c b/gcc/testsuite/gcc.target/i386/strict-cc.c
  88 new file mode 100644
  89 index 00000000000..fa0543e52ff
  90 --- /dev/null
  91 +++ b/gcc/testsuite/gcc.target/i386/strict-cc.c
  92 @@ -0,0 +1,24 @@
  93 +/* { dg-do compile { target { ilp32 } } } */
  94 +/* { dg-options "-O2 -funit-at-a-time -fstrict-calling-conventions"  } */
  95 +/* { dg-final { scan-assembler "pushl.*\\\$1" } } */
  96 +/* { dg-final { scan-assembler "pushl.*\\\$2" } } */
  97 +/* { dg-final { scan-assembler "pushl.*\\\$3" } } */
  98 +/* { dg-final { scan-assembler "pushl.*\\\$4" } } */
  99 +/* { dg-final { scan-assembler "pushl.*\\\$5" } } */
 100 +
 101 +#include <stdio.h>
 102 +
 103 +/* Verify that local calling convention is not used if strict conventions.  */
 104 +static int t(int, int, int, int, int) __attribute__ ((noinline));
 105 +
 106 +int
 107 +m()
 108 +{
 109 +    t(1, 2, 3, 4, 5);
 110 +}
 111 +
 112 +static int
 113 +t(int a, int b, int c, int d, int e)
 114 +{
 115 +    printf("%d\n", a, b, c, d, e);
 116 +}
 117 --
 118 2.31.1
 119