[hjl@gnu-6 gcc]$ cat x.c float foo (void) { return 0; } [hjl@gnu-6 gcc]$ ./xgcc -B./ -march=lakemont -S x.c -m32 [hjl@gnu-6 gcc]$ cat x.s .file "x.c" .text .globl foo .type foo, @function foo: .LFB0: .cfi_startproc pushl %ebp .cfi_def_cfa_offset 8 .cfi_offset 5, -8 movl %esp, %ebp .cfi_def_cfa_register 5 fldz popl %ebp .cfi_restore 5 .cfi_def_cfa 4, 4 ret .cfi_endproc .LFE0: .size foo, .-foo .ident "GCC: (GNU) 6.0.0 20151006 (experimental)" .section .note.GNU-stack,"",@progbits [hjl@gnu-6 gcc]$ We should issue an error if -march=lakemont is used without -miacmu.
(In reply to H.J. Lu from comment #0) > We should issue an error if -march=lakemont is used without -miacmu. We should issue an error if -march=lakemont is used without -mno-80387, not without -miamcu.
(In reply to H.J. Lu from comment #1) > (In reply to H.J. Lu from comment #0) > > We should issue an error if -march=lakemont is used without -miacmu. > > We should issue an error if -march=lakemont is used without -mno-80387, > not without -miamcu. -march=lakemont should imply -mno-80387.
Patch posted at: https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01369.html The same test with this patch: objdump -d test.o test.o: file format elf32-i386 Disassembly of section .text: 00000000 <foo>: 0: 55 push %ebp 1: 89 e5 mov %esp,%ebp 3: a1 00 00 00 00 mov 0x0,%eax 8: 5d pop %ebp 9: c3 ret
I have a patch that moves -m80387 to ISA flags.
(In reply to Uroš Bizjak from comment #4) > I have a patch that moves -m80387 to ISA flags. Not really. To be attached much simpler patch introduces PTA_NO_80387 and changes target flags instead.
Created attachment 36516 [details] Patch that introduces PTA_NO_80387
Created attachment 36517 [details] V2 patch that introduces PTA_NO_80387
(In reply to Uroš Bizjak from comment #7) > Created attachment 36517 [details] > V2 patch that introduces PTA_NO_80387 We need some testcases to verify it works on command line as well as with __attribute__((target("arch=...."))).
Author: hjl Date: Tue Oct 20 15:12:37 2015 New Revision: 229082 URL: https://gcc.gnu.org/viewcvs?rev=229082&root=gcc&view=rev Log: Properly handle -miamcu and -march=lakemont -miamcu specifies how parameters are passed to functions and how value is returned from a function. Inside function, we can use instructions supported by -march=XXX. -miamcu -march=haswell can generate x87, SSE and AVX instructions as long as the IA MCU psABI is followed. But since Lakemont processor doesn't support x87 instructions, we shouldn't generate x87 instructions with -march=lakemont. This patch separates code generation from -miamcu and makes -march=lakemont not to generate x87 instructions. gcc/ PR target/67963 PR target/67985 * common/config/i386/i386-common.c (ix86_handle_option): Remove OPT_miamcu handling. * config/i386/i386.c (PTA_NO_80387): New macro. (processor_alias_table): Add PTA_NO_80387 to lakemont. (ix86_option_override_internal): Update MASK_80387 from PTA_NO_80387. Don't warn x87/MMX/SSE/AVX for -miamcu. Warn SSE math only if 80387 is supported. Don't change MASK_FLOAT_RETURNS. (ix86_valid_target_attribute_tree): Enable FPMATH_387 only if 80387 is supported. * config/i386/i386.h (TARGET_FLOAT_RETURNS_IN_80387): True only if TARGET_80387 is true and TARGET_IAMCU is false. (TARGET_FLOAT_RETURNS_IN_80387_P): True only if TARGET_80387_P is true and TARGET_IAMCU_P is false. gcc/testsuite/ PR target/67963 PR target/67985 * gcc.target/i386/pr67963-1.c: New test. * gcc.target/i386/pr67963-2.c: Likewise. * gcc.target/i386/pr67963-3.c: Likewise. * gcc.target/i386/pr67985-1.c: Likewise. * gcc.target/i386/pr67985-2.c: Likewise. * gcc.target/i386/pr67985-3.c: Likewise. Added: trunk/gcc/testsuite/gcc.target/i386/pr67963-1.c trunk/gcc/testsuite/gcc.target/i386/pr67963-2.c trunk/gcc/testsuite/gcc.target/i386/pr67963-3.c trunk/gcc/testsuite/gcc.target/i386/pr67985-1.c trunk/gcc/testsuite/gcc.target/i386/pr67985-2.c trunk/gcc/testsuite/gcc.target/i386/pr67985-3.c Modified: trunk/gcc/ChangeLog trunk/gcc/common/config/i386/i386-common.c trunk/gcc/config/i386/i386.c trunk/gcc/config/i386/i386.h trunk/gcc/testsuite/ChangeLog
Fixed.