[gcc r12-7335] arm: Add GENERAL_AND_VPR_REGS regclass

[gcc r12-7335] arm: Add GENERAL_AND_VPR_REGS regclass

[Christophe Lyon]

https://gcc.gnu.org/g:bf3e36fbf13f0db44a79988036cb9c042288841a

commit r12-7335-gbf3e36fbf13f0db44a79988036cb9c042288841a
Author: Christophe Lyon <christophe.lyon@arm.com>
Date:   Wed Oct 13 09:16:09 2021 +0000

    arm: Add GENERAL_AND_VPR_REGS regclass
    
    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.
    
    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.
    
    Most of the work of this patch series was carried out while I was
    working at STMicroelectronics as a Linaro assignee.
    
    2022-02-22  Christophe Lyon  <christophe.lyon@arm.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.cc (arm_hard_regno_nregs): Handle VPR.

Diff:
---
 gcc/config/arm/arm.cc | 3 +++
 gcc/config/arm/arm.h  | 7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index 663f4595050..9c19589186f 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -25339,6 +25339,9 @@ 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);
+
   if (TARGET_32BIT
       && regno > PC_REGNUM
       && regno != FRAME_POINTER_REGNUM
diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index f52724d01ad..61c02218b78 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -1287,6 +1287,7 @@ enum reg_class
   SFP_REG,
   AFP_REG,
   VPR_REG,
+  GENERAL_AND_VPR_REGS,
   ALL_REGS,
   LIM_REG_CLASSES
 };
@@ -1316,6 +1317,7 @@ enum reg_class
   "SFP_REG",		\
   "AFP_REG",		\
   "VPR_REG",		\
+  "GENERAL_AND_VPR_REGS", \
   "ALL_REGS"		\
 }
 
@@ -1344,6 +1346,7 @@ enum reg_class
   { 0x00000000, 0x00000000, 0x00000000, 0x00000040 }, /* SFP_REG */	\
   { 0x00000000, 0x00000000, 0x00000000, 0x00000080 }, /* AFP_REG */	\
   { 0x00000000, 0x00000000, 0x00000000, 0x00000400 }, /* VPR_REG.  */	\
+  { 0x00005FFF, 0x00000000, 0x00000000, 0x00000400 }, /* GENERAL_AND_VPR_REGS.  */ \
   { 0xFFFF7FFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x0000000F }  /* ALL_REGS.  */	\
 }
 
@@ -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))
 
 /* If defined, gives a class of registers that cannot be used as the
    operand of a SUBREG that changes the mode of the object illegally.  */