Hello!
"*cmp<X87MODEF:mode>_<SWI24:mode>_cc_i387" is never matched by
combine. The order of operands in x87 ficom compare is forced by
combine in simplify_comparison () function. Float operator is treated
as RTX_OBJ with a precedence over other operators and is always put in
the first place.
Patch defines TARGET_CANONICALIZE_COMPARISON target hook to swap
condition and operands to match ficom instruction.
2017-10-11 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.c (ix86_canonicalize_comparison): New function.
(TARGET_CANONICALIZE_COMPARISON): Define.
testsuite/ChangeLog:
2017-10-11 Uros Bizjak <ubiz...@gmail.com>
* gcc.target/i386/387-ficom-2.c: New test.
Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.
Committed to mainline SVN.
Uros.
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c (revision 253653)
+++ config/i386/i386.c (working copy)
@@ -4792,6 +4792,30 @@ ix86_conditional_register_usage (void)
fixed_regs[i] = call_used_regs[i] = 1, reg_names[i] = "";
}
+/* Canonicalize a comparison from one we don't have to one we do have. */
+
+static void
+ix86_canonicalize_comparison (int *code, rtx *op0, rtx *op1,
+ bool op0_preserve_value)
+{
+ /* The order of operands in x87 ficom compare is forced by combine in
+ simplify_comparison () function. Float operator is treated as RTX_OBJ
+ with a precedence over other operators and is always put in the first
+ place. Swap condition and operands to match ficom instruction. */
+ if (!op0_preserve_value
+ && GET_CODE (*op0) == FLOAT && MEM_P (XEXP (*op0, 0)) && REG_P (*op1))
+ {
+ enum rtx_code scode = swap_condition ((enum rtx_code) *code);
+
+ /* We are called only for compares that are split to SAHF instruction.
+ Ensure that we have setcc/jcc insn for the swapped condition. */
+ if (ix86_fp_compare_code_to_integer (scode) != UNKNOWN)
+ {
+ std::swap (*op0, *op1);
+ *code = (int) scode;
+ }
+ }
+}
/* Save the current options */
@@ -49649,6 +49673,9 @@ ix86_run_selftests (void)
#undef TARGET_CONDITIONAL_REGISTER_USAGE
#define TARGET_CONDITIONAL_REGISTER_USAGE ix86_conditional_register_usage
+#undef TARGET_CANONICALIZE_COMPARISON
+#define TARGET_CANONICALIZE_COMPARISON ix86_canonicalize_comparison
+
#undef TARGET_LOOP_UNROLL_ADJUST
#define TARGET_LOOP_UNROLL_ADJUST ix86_loop_unroll_adjust
Index: testsuite/gcc.target/i386/387-ficom-2.c
===================================================================
--- testsuite/gcc.target/i386/387-ficom-2.c (nonexistent)
+++ testsuite/gcc.target/i386/387-ficom-2.c (working copy)
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target ia32 } */
+/* { dg-skip-if "" { *-*-* } { "-march=*" } { "-march=i386" } } */
+/* { dg-options "-Os -march=i386 -ffast-math -masm=att" } */
+
+#include "387-ficom-1.c"
+
+/* { dg-final { scan-assembler-times "ficomps" 3 } } */
+/* { dg-final { scan-assembler-times "ficompl" 3 } } */
