Hi Christophe,
On 13/01/2022 14:56, Christophe Lyon via Gcc-patches wrote:
At some point during the development of this patch series, it appeared
that in some cases the register allocator wants “VPR or general”
rather than “VPR or general or FP” (which is the same thing as
ALL_REGS). The series does not seem to require this anymore, but it
seems to be a good thing to do anyway, to give the register allocator
more freedom.
Not sure I fully understand this, but I guess it creates an extra class
the register allocator can use to group things that can go into VPR or
general reg?
CLASS_MAX_NREGS and arm_hard_regno_nregs need adjustment to avoid a
regression in gcc.dg/stack-usage-1.c when compiled with -mthumb
-mfloat-abi=hard -march=armv8.1-m.main+mve.fp+fp.dp.
I have not looked into this failure, but ...
2022-01-13 Christophe Lyon <christophe.l...@foss.st.com>
gcc/
* config/arm/arm.h (reg_class): Add GENERAL_AND_VPR_REGS.
(REG_CLASS_NAMES): Likewise.
(REG_CLASS_CONTENTS): Likewise.
(CLASS_MAX_NREGS): Handle VPR.
* config/arm/arm.c (arm_hard_regno_nregs): Handle VPR.
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index bb75921f32d..c3559ca8703 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -25287,6 +25287,9 @@ thumb2_asm_output_opcode (FILE * stream)
static unsigned int
arm_hard_regno_nregs (unsigned int regno, machine_mode mode)
{
+ if (IS_VPR_REGNUM (regno))
+ return CEIL (GET_MODE_SIZE (mode), 2);
When do we ever want to use more than 1 register for VPR?
@@ -1453,7 +1456,9 @@ extern const char *fp_sysreg_names[NB_FP_SYSREGS];
ARM regs are UNITS_PER_WORD bits.
FIXME: Is this true for iWMMX? */
#define CLASS_MAX_NREGS(CLASS, MODE) \
- (ARM_NUM_REGS (MODE))
+ (CLASS == VPR_REG) \
+ ? CEIL (GET_MODE_SIZE (MODE), 2) \
+ : (ARM_NUM_REGS (MODE))
Same.
