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[RS6000] PR11848 rs6000_emit_move long double split

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This split is disabled for power7 and up, so we don't often see its
bad effects.  However, on a powerpc-linux compiler (which defaults
to PPC750 judging from rs6000/sysv4.h) we see

	long double ld1 (void) { return 1.0L; }

compiled with -msoft-float -O2 -S resulting in

	ld1:
		li 3,0
		li 4,0
		mr 6,4
		mr 5,3
		li 4,0
		lis 3,0x3ff0
		blr

Things go awry in init-regs, with the TFmode reg being initialized to
zero on seeing the subreg from the split.  (And that initialization
itself is split by rs6000_emit_move!)  Later passes apparently don't
clean up the rubbish.

Since the split was added for Darwin (as the comment says), let's get
rid of it on other targets.

	* config/rs6000/rs6000.c (rs6000_emit_move): Disable long
	double split for targets other than Darwin.

From-SVN: r266610
This commit is contained in:
Alan Modra 2018-11-29 15:33:01 +10:30
parent aa74f2217d
commit 9caa6732f9
2 changed files with 8 additions and 3 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,8 @@
2018-11-29 Alan Modra <amodra@gmail.com>
* config/rs6000/rs6000.c (rs6000_emit_move): Disable long
double split for targets other than Darwin.
2018-11-29 Alan Modra <amodra@gmail.com>
* config/rs6000/rs6000.md (movdi_internal64): Correct lengths.
@ -692,7 +697,7 @@
2018-11-23 Christoph Muellner <christoph.muellner@theobroma-systems.com>
* config/aarch64/aarch64-cores.def: Define emag.
* config/aarch64/aarch64-cores.def: Define emag.
* config/aarch64/aarch64-tune.md: Regenerated with emag.
* config/aarch64/aarch64.c (emag_tunings): New struct.
* doc/invoke.texi: Document mtune value.

4
gcc/config/rs6000/rs6000.c
View File

@ -9967,8 +9967,8 @@ rs6000_emit_move (rtx dest, rtx source, machine_mode mode)
/* 128-bit constant floating-point values on Darwin should really be loaded
as two parts. However, this premature splitting is a problem when DFmode
values can go into Altivec registers. */
if (FLOAT128_IBM_P (mode) && !reg_addr[DFmode].scalar_in_vmx_p
&& GET_CODE (operands[1]) == CONST_DOUBLE)
if (TARGET_MACHO && CONST_DOUBLE_P (operands[1]) && FLOAT128_IBM_P (mode)
&& !reg_addr[DFmode].scalar_in_vmx_p)
{
rs6000_emit_move (simplify_gen_subreg (DFmode, operands[0], mode, 0),
simplify_gen_subreg (DFmode, operands[1], mode, 0),