From 62a02d25b6e5d9f92c205260daa11355d0c62532 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Sat, 17 Feb 2018 05:20:42 -0800 Subject: Add .nop assembler directive Implement the '.nop SIZE[, CONTROL]' assembler directive, which emits SIZE bytes filled with no-op instructions. SIZE is absolute expression. The optional CONTROL byte controls how no-op instructions should be generated. If the comma and @var{control} are omitted, CONTROL is assumed to be zero. For Intel 80386 and AMD x86-64 targets, CONTROL byte specifies the size limit of a single no-op instruction. The valid values of CONTROL byte are between 0 and 8 for 16-bit mode, between 0 and 10 for 32-bit mode, between 0 and 11 for 64-bit mode. When 0 is used, the no-op size limit is set to the maximum supported size. 2 new relax states, rs_space_nop and rs_fill_nop, are added to enum _relax_state, which are similar to rs_space and rs_fill, respectively, but they fill with no-op instructions, instead of a single byte. A target backend must override the default md_generate_nops to generate proper no-op instructions. Otherwise, an error of unimplemented .nop directive will be issued whenever .nop directive is used. * NEWS: Mention .nop directive. * as.h (_relax_state): Add rs_space_nop and rs_fill_nop. * read.c (potable): Add .nop. (s_nop): New function. * read.h (s_nop): New prototype. * write.c (cvt_frag_to_fill): Handle rs_space_nop and rs_fill_nop. (md_generate_nops): New function. (relax_segment): Likewise. (write_contents): Use md_generate_nops for rs_fill_nop. * config/tc-i386.c (alt64_11): New. (alt64_patt): Likewise. (md_convert_frag): Handle rs_space_nop. (i386_output_nops): New function. (i386_generate_nops): Likewise. (i386_align_code): Call i386_output_nops. * config/tc-i386.h (i386_generate_nops): New. (md_generate_nops): Likewise. * doc/as.texinfo: Document .nop directive. * testsuite/gas/i386/i386.exp: Run .nop directive tests. * testsuite/gas/i386/nop-1.d: New file. * testsuite/gas/i386/nop-1.s: Likewise. * testsuite/gas/i386/nop-2.d: Likewise. * testsuite/gas/i386/nop-2.s: Likewise. * testsuite/gas/i386/nop-3.d: Likewise. * testsuite/gas/i386/nop-3.s: Likewise. * testsuite/gas/i386/nop-4.d: Likewise. * testsuite/gas/i386/nop-4.s: Likewise. * testsuite/gas/i386/nop-5.d: Likewise. * testsuite/gas/i386/nop-5.s: Likewise. * testsuite/gas/i386/nop-6.d: Likewise. * testsuite/gas/i386/nop-6.s: Likewise. * testsuite/gas/i386/nop-bad-1.l: Likewise. * testsuite/gas/i386/nop-bad-1.s: Likewise. * testsuite/gas/i386/x86-64-nop-1.d: Likewise. * testsuite/gas/i386/x86-64-nop-2.d: Likewise. * testsuite/gas/i386/x86-64-nop-3.d: Likewise. * testsuite/gas/i386/x86-64-nop-4.d: Likewise. * testsuite/gas/i386/x86-64-nop-5.d: Likewise. * testsuite/gas/i386/x86-64-nop-6.d: Likewise. --- gas/NEWS | 3 +++ 1 file changed, 3 insertions(+) (limited to 'gas/NEWS') diff --git a/gas/NEWS b/gas/NEWS index a591a7b..27ee306 100644 --- a/gas/NEWS +++ b/gas/NEWS @@ -1,5 +1,8 @@ -*- text -*- +* Add support for .nop directive. It is currently supported only for + x86 targets. + Changes in 2.30: * Add support for loaction views in DWARF debug line information. -- cgit v1.1