[PATCH v3 04/15] arm: Add GENERAL_AND_VPR_REGS regclass

[Christophe Lyon <christophe.lyon@foss.st.com>]

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.

2022-01-13  Christophe Lyon  <christophe.lyon@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);
+
   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 dacce2b7f08..2416fb5ef64 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.  */
-- 
2.25.1