From a50187b2c6c28be79a32332e06a572cf08683de3 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 15 Jun 2021 07:59:44 +0200 Subject: [PATCH] x86: harmonize disp with imm handling Certain disp values may trigger "... shortened to ..." warnings when equivalent imm ones don't. In some of the cases there are also differences (for non-64-bit code) between BFD64 and !BFD64 builds. The resulting encodings (i.e. use [or not] of the shorter disp8 / imm8 forms) are also different in some cases. Make this handling consistent. Note that using equivalent 16-bit mode displacements / immediates continues to expose entirely different behavior (see the disp-imm-16 testcase added by an earlier patch). This may want to be the subject of further changes, but it'll then quickly become obvious that e.g. keying use of extend_to_32bit_address() to non-64-bit mode isn't appropriate either: Once we allow wrapping operands, we would better do so consistently, in which case all of this would need to become dependent upon address or operand size instead of mode. --- gas/ChangeLog | 10 ++++++ gas/config/tc-i386.c | 51 +++++++++++++++------------- gas/testsuite/gas/i386/disp-imm-32.d | 21 ++++++++++++ gas/testsuite/gas/i386/disp-imm-32.s | 17 ++++++++++ gas/testsuite/gas/i386/i386.exp | 3 ++ 5 files changed, 79 insertions(+), 23 deletions(-) create mode 100644 gas/testsuite/gas/i386/disp-imm-32.d create mode 100644 gas/testsuite/gas/i386/disp-imm-32.s diff --git a/gas/ChangeLog b/gas/ChangeLog index 97bb57bd477..0a59cd74d6a 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,3 +1,13 @@ +2021-06-15 Jan Beulich + + * config/tc-i386.c (optimize_disp): Generalize disp32 part of + the BFD64-only logic to also apply to non-64-bit code. + (i386_finalize_displacement): Use extend_to_32bit_address for + non-64-bit code. Drop now redundant O_constant checks. + * testsuite/gas/i386/disp-imm-32.s, + testsuite/gas/i386/disp-imm-32.d: New. + * testsuite/gas/i386/i386.exp: Run new test. + 2021-06-15 Jan Beulich * config/tc-i386.c (offset_in_range): Replace uses of diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c index da4998caaf5..e6276dcab5c 100644 --- a/gas/config/tc-i386.c +++ b/gas/config/tc-i386.c @@ -5905,26 +5905,24 @@ optimize_disp (void) } #ifdef BFD64 - if (flag_code == CODE_64BIT) + /* Optimize 64-bit displacement to 32-bit for 64-bit BFD. */ + if ((i.types[op].bitfield.disp32 + || (flag_code == CODE_64BIT + && want_disp32 (current_templates->start))) + && fits_in_unsigned_long (op_disp)) { - /* Optimize 64-bit displacement to 32-bit for 64-bit BFD. */ - if ((i.types[op].bitfield.disp32 - || want_disp32 (current_templates->start)) - && fits_in_unsigned_long (op_disp)) - { - /* If this operand is at most 32 bits, convert - to a signed 32 bit number and don't use 64bit - displacement. */ - op_disp = (op_disp ^ ((offsetT) 1 << 31)) - ((addressT) 1 << 31); - i.types[op].bitfield.disp64 = 0; - i.types[op].bitfield.disp32 = 1; - } + /* If this operand is at most 32 bits, convert + to a signed 32 bit number and don't use 64bit + displacement. */ + op_disp = (op_disp ^ ((offsetT) 1 << 31)) - ((addressT) 1 << 31); + i.types[op].bitfield.disp64 = 0; + i.types[op].bitfield.disp32 = 1; + } - if (fits_in_signed_long (op_disp)) - { - i.types[op].bitfield.disp64 = 0; - i.types[op].bitfield.disp32s = 1; - } + if (flag_code == CODE_64BIT && fits_in_signed_long (op_disp)) + { + i.types[op].bitfield.disp64 = 0; + i.types[op].bitfield.disp32s = 1; } #endif if ((i.types[op].bitfield.disp32 @@ -11019,9 +11017,18 @@ i386_finalize_displacement (segT exp_seg ATTRIBUTE_UNUSED, expressionS *exp, ret = 0; } + else if (exp->X_op == O_constant) + { + /* Sizing gets taken care of by optimize_disp(). + + If not 64bit, sign/zero extend val, to account for wraparound + when !BFD64. */ + if (flag_code != CODE_64BIT) + exp->X_add_number = extend_to_32bit_address (exp->X_add_number); + } + #if (defined (OBJ_AOUT) || defined (OBJ_MAYBE_AOUT)) - else if (exp->X_op != O_constant - && OUTPUT_FLAVOR == bfd_target_aout_flavour + else if (OUTPUT_FLAVOR == bfd_target_aout_flavour && exp_seg != absolute_section && exp_seg != text_section && exp_seg != data_section @@ -11034,9 +11041,7 @@ i386_finalize_displacement (segT exp_seg ATTRIBUTE_UNUSED, expressionS *exp, } #endif - if (current_templates->start->opcode_modifier.jump == JUMP_BYTE - /* Constants get taken care of by optimize_disp(). */ - && exp->X_op != O_constant) + else if (current_templates->start->opcode_modifier.jump == JUMP_BYTE) i.types[this_operand].bitfield.disp8 = 1; /* Check if this is a displacement only operand. */ diff --git a/gas/testsuite/gas/i386/disp-imm-32.d b/gas/testsuite/gas/i386/disp-imm-32.d new file mode 100644 index 00000000000..dc712b96269 --- /dev/null +++ b/gas/testsuite/gas/i386/disp-imm-32.d @@ -0,0 +1,21 @@ +#objdump: -dw +#name: i386 displacements / immediates (32-bit) + +.*: +file format .* + +Disassembly of section .text: + +0+ : +[ ]*[a-f0-9]+: 8b 40 01 mov 0x1\(%eax\),%eax +[ ]*[a-f0-9]+: 62 f1 7c 48 28 40 01 vmovaps 0x40\(%eax\),%zmm0 +[ ]*[a-f0-9]+: 83 c1 01 add \$0x1,%ecx +[ ]*[a-f0-9]+: 8b 00 mov \(%eax\),%eax +[ ]*[a-f0-9]+: 62 f1 7c 48 28 00 vmovaps \(%eax\),%zmm0 +[ ]*[a-f0-9]+: 83 c1 00 add \$0x0,%ecx +[ ]*[a-f0-9]+: 8b 40 ff mov -0x1\(%eax\),%eax +[ ]*[a-f0-9]+: 62 f1 7c 48 28 40 ff vmovaps -0x40\(%eax\),%zmm0 +[ ]*[a-f0-9]+: 83 c1 ff add \$0xffffffff,%ecx +[ ]*[a-f0-9]+: 8b 40 01 mov 0x1\(%eax\),%eax +[ ]*[a-f0-9]+: 62 f1 7c 48 28 40 01 vmovaps 0x40\(%eax\),%zmm0 +[ ]*[a-f0-9]+: 83 c1 01 add \$0x1,%ecx +#pass diff --git a/gas/testsuite/gas/i386/disp-imm-32.s b/gas/testsuite/gas/i386/disp-imm-32.s new file mode 100644 index 00000000000..5145d605a42 --- /dev/null +++ b/gas/testsuite/gas/i386/disp-imm-32.s @@ -0,0 +1,17 @@ + .text +disp_imm: + mov -0xffffffff(%eax), %eax + vmovaps -0xffffffc0(%eax), %zmm0 + add $-0xffffffff, %ecx + + mov -0xffffffff-1(%eax), %eax + vmovaps -0xffffffc0-0x40(%eax), %zmm0 + add $-0xffffffff-1, %ecx + + mov -0xffffffff-2(%eax), %eax + vmovaps -0xffffffc0-0x80(%eax), %zmm0 + add $-0xffffffff-2, %ecx + + mov -0x1ffffffff(%eax), %eax + vmovaps -0x1ffffffc0(%eax), %zmm0 + add $-0x1ffffffff, %ecx diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp index 4112a1d171f..8f41778034c 100644 --- a/gas/testsuite/gas/i386/i386.exp +++ b/gas/testsuite/gas/i386/i386.exp @@ -88,6 +88,9 @@ if [gas_32_check] then { run_dump_test "disp-intel" run_dump_test "disp32" run_list_test "disp-imm-16" + if { [gas_bfd64_check] } { + run_dump_test "disp-imm-32" + } run_dump_test "vmx" run_dump_test "vmfunc" run_dump_test "smx" -- 2.30.2