After
commit 965564eafb721f8000013a3112f1bba8d8fae32b
Author: Richard Sandiford <richard.sandif...@arm.com>
Date: Tue Jul 29 15:58:34 2025 +0100
simplify-rtx: Simplify subregs of logic ops
make_compound_operation_int gets
(lshiftrt:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])))
instead of
(and:DI (lshiftrt:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8]))
(const_int 255 [0xff]))
If this is for SET of ZERO_EXTRACT destination:
(zero_extract:DI (reg/v:DI 103 [ a ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
make an extraction out of the logical right shift
(zero_extract:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])
(const_int 8 [0x8]))
to convert
(set (zero_extract:DI (reg/v:DI 103 [ a ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(lshiftrt:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])))
to
(set (zero_extract:DI (reg/v:DI 103 [ a ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(zero_extract:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])
(const_int 8 [0x8])))
PR target/121306
* combine.cc (simplify_set): Pass dest to make_compound_operation.
(make_compound_operation_int): Add an rtx argument for
destination and pass it to make_compound_operation. For a logical
right shift if the destination is ZERO_EXTRACT with constant start
and width, make an extraction.
(make_compound_operation): Add an rtx argument for destination
and pass it to make_compound_operation_int.
* rtl.h (make_compound_operation): Add an rtx argument, default
to nullptr.
Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
gcc/combine.cc | 34 ++++++++++++++++++++++++++++++----
gcc/rtl.h | 2 +-
2 files changed, 31 insertions(+), 5 deletions(-)
diff --git a/gcc/combine.cc b/gcc/combine.cc
index 4dbc1f6a4a4..42dff7db153 100644
--- a/gcc/combine.cc
+++ b/gcc/combine.cc
@@ -7027,7 +7027,7 @@ simplify_set (rtx x)
{
/* Get SET_SRC in a form where we have placed back any
compound expressions. Then do the checks below. */
- src = make_compound_operation (src, SET);
+ src = make_compound_operation (src, SET, dest);
SUBST (SET_SRC (x), src);
}
@@ -8070,7 +8070,8 @@ extract_left_shift (scalar_int_mode mode, rtx x, int
count)
static rtx
make_compound_operation_int (scalar_int_mode mode, rtx *x_ptr,
enum rtx_code in_code,
- enum rtx_code *next_code_ptr)
+ enum rtx_code *next_code_ptr,
+ rtx dest)
{
rtx x = *x_ptr;
enum rtx_code next_code = *next_code_ptr;
@@ -8343,6 +8344,31 @@ make_compound_operation_int (scalar_int_mode mode, rtx
*x_ptr,
XEXP (x, 1));
break;
}
+ else if (in_code == SET
+ && dest
+ && GET_CODE (dest) == ZERO_EXTRACT
+ && CONST_INT_P (XEXP (dest, 1))
+ && CONST_INT_P (XEXP (dest, 2)))
+ {
+ /* If this is used for SET of ZERO_EXTRACT destination with
+ constant start and width:
+
+ (set (zero_extract:DI (reg/v:DI 103 [ a ])
+ (const_int 8 [0x8])
+ (const_int 8 [0x8]))
+ (lshiftrt:DI (and:DI (reg:DI 110 [ b ])
+ (reg/v:DI 103 [ a ]))
+ (const_int 8 [0x8])))
+
+ make an extraction. */
+ new_rtx = make_compound_operation (XEXP (x, 0), next_code);
+ new_rtx = make_extraction (mode, new_rtx,
+ INTVAL (XEXP (dest, 2)),
+ XEXP (x, 1),
+ INTVAL (XEXP (dest, 1)), true,
+ false, in_code == COMPARE);
+ break;
+ }
/* fall through */
@@ -8503,7 +8529,7 @@ make_compound_operation_int (scalar_int_mode mode, rtx
*x_ptr,
precisely it is an equality comparison against zero. */
rtx
-make_compound_operation (rtx x, enum rtx_code in_code)
+make_compound_operation (rtx x, enum rtx_code in_code, rtx dest)
{
enum rtx_code code = GET_CODE (x);
const char *fmt;
@@ -8524,7 +8550,7 @@ make_compound_operation (rtx x, enum rtx_code in_code)
if (is_a <scalar_int_mode> (GET_MODE (x), &mode))
{
rtx new_rtx = make_compound_operation_int (mode, &x, in_code,
- &next_code);
+ &next_code, dest);
if (new_rtx)
return new_rtx;
code = GET_CODE (x);
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 5bd0bd4d168..e4f197157b0 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -4287,7 +4287,7 @@ extern bool validate_subreg (machine_mode, machine_mode,
/* In combine.cc */
extern unsigned int extended_count (const_rtx, machine_mode, bool);
extern rtx remove_death (unsigned int, rtx_insn *);
-extern rtx make_compound_operation (rtx, enum rtx_code);
+extern rtx make_compound_operation (rtx, enum rtx_code, rtx = nullptr);
/* In sched-rgn.cc. */
extern void schedule_insns (void);
--
2.50.1
