[PATCH] aarch64: Fix error in THE system register checking

[PATCH] aarch64: Fix error in THE system register checking

[Victor Do Nascimento]

The erroneous omission of a "reg_value == " in the THE system register
encoding check added in [1] led to an error which was not picked up in
GCC but which was flagged in Clang due to its use of
[-Werror,-Wconstant-logical-operand] check.  Together with this fix we
add a new test for the THE registers to pick up their illegal use,
adding an extra and important layer of validation.

Furthermore, in separating system register from instruction
implementation (with which only the former was of concern in the cited
patch), additions made to `aarch64-tbl.h' are rolled back so
that these can be added later when adding THE instructions to the
codebase, a more natural place for these changes.

[1] https://sourceware.org/pipermail/binutils/2023-November/130314.html

opcodes/ChangeLog:

	* aarch64-opc.c (aarch64_sys_ins_reg_supported_p): Fix typo.
	* aarch64-tbl.h (THE): Remove.
	 (aarch64_feature_set aarch64_feature_the): Likewise.

gas/ChangeLog:

	* testsuite/gas/aarch64/illegal-sysreg-8.l: Add tests for THE
	system registers.
	* testsuite/gas/aarch64/illegal-sysreg-8.s: Likewise.
---
 gas/testsuite/gas/aarch64/illegal-sysreg-8.l | 8 ++++++++
 gas/testsuite/gas/aarch64/illegal-sysreg-8.s | 2 ++
 opcodes/aarch64-opc.c                        | 2 +-
 opcodes/aarch64-tbl.h                        | 3 ---
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/gas/testsuite/gas/aarch64/illegal-sysreg-8.l b/gas/testsuite/gas/aarch64/illegal-sysreg-8.l
index 6a5f8fe567c..773e8d80f7a 100644
--- a/gas/testsuite/gas/aarch64/illegal-sysreg-8.l
+++ b/gas/testsuite/gas/aarch64/illegal-sysreg-8.l
@@ -3,6 +3,14 @@
 .*: *Info: macro .*
 .*: Error: selected processor does not support system register name 'ccsidr2_el1'
 .*: *Info: macro .*
+.*: Error: selected processor does not support system register name 'rcwmask_el1'
+.*: *Info: macro .*
+.*: Error: selected processor does not support system register name 'rcwmask_el1'
+.*: *Info: macro .*
+.*: Error: selected processor does not support system register name 'rcwsmask_el1'
+.*: *Info: macro .*
+.*: Error: selected processor does not support system register name 'rcwsmask_el1'
+.*: *Info: macro .*
 .*: Error: selected processor does not support system register name 'trfcr_el1'
 .*: *Info: macro .*
 .*: Error: selected processor does not support system register name 'trfcr_el1'
diff --git a/gas/testsuite/gas/aarch64/illegal-sysreg-8.s b/gas/testsuite/gas/aarch64/illegal-sysreg-8.s
index a1a7ae6faed..0ce61ddfe45 100644
--- a/gas/testsuite/gas/aarch64/illegal-sysreg-8.s
+++ b/gas/testsuite/gas/aarch64/illegal-sysreg-8.s
@@ -16,6 +16,8 @@
 	.arch	armv8.2-a
 
 	roreg	ccsidr2_el1
+	rwreg	rcwmask_el1
+	rwreg	rcwsmask_el1
 
 	.arch	armv8.3-a
 
diff --git a/opcodes/aarch64-opc.c b/opcodes/aarch64-opc.c
index 5a0f0e9f52e..f8d4c1a4d33 100644
--- a/opcodes/aarch64-opc.c
+++ b/opcodes/aarch64-opc.c
@@ -5037,7 +5037,7 @@ aarch64_sys_ins_reg_supported_p (const aarch64_feature_set features,
     return true;
 
   if ((reg_value == CPENC (3,0,13,0,3)
-       || CPENC (3,0,13,0,6))
+       || reg_value == CPENC (3,0,13,0,6))
       && AARCH64_CPU_HAS_FEATURE (features, THE))
     return true;
 
diff --git a/opcodes/aarch64-tbl.h b/opcodes/aarch64-tbl.h
index feea209ea30..74fd6695d81 100644
--- a/opcodes/aarch64-tbl.h
+++ b/opcodes/aarch64-tbl.h
@@ -2578,8 +2578,6 @@ static const aarch64_feature_set aarch64_feature_chk =
   AARCH64_FEATURE (CHK);
 static const aarch64_feature_set aarch64_feature_gcs =
   AARCH64_FEATURE (GCS);
-static const aarch64_feature_set aarch64_feature_the =
-  AARCH64_FEATURE (THE);
 
 #define CORE		&aarch64_feature_v8
 #define FP		&aarch64_feature_fp
@@ -2641,7 +2639,6 @@ static const aarch64_feature_set aarch64_feature_the =
 #define CSSC	  &aarch64_feature_cssc
 #define CHK	  &aarch64_feature_chk
 #define GCS	  &aarch64_feature_gcs
-#define THE	  &aarch64_feature_the
 
 #define CORE_INSN(NAME,OPCODE,MASK,CLASS,OP,OPS,QUALS,FLAGS) \
   { NAME, OPCODE, MASK, CLASS, OP, CORE, OPS, QUALS, FLAGS, 0, 0, NULL }
-- 
2.41.0

Re: [PATCH] aarch64: Fix error in THE system register checking

[Nick Clifton]

Hi Victor,

> The erroneous omission of a "reg_value == " in the THE system register
> encoding check added in [1] led to an error which was not picked up in
> GCC but which was flagged in Clang due to its use of
> [-Werror,-Wconstant-logical-operand] check.  Together with this fix we
> add a new test for the THE registers to pick up their illegal use,
> adding an extra and important layer of validation.
> 
> Furthermore, in separating system register from instruction
> implementation (with which only the former was of concern in the cited
> patch), additions made to `aarch64-tbl.h' are rolled back so
> that these can be added later when adding THE instructions to the
> codebase, a more natural place for these changes.
> 
> [1] https://sourceware.org/pipermail/binutils/2023-November/130314.html
> 
> opcodes/ChangeLog:
> 
> 	* aarch64-opc.c (aarch64_sys_ins_reg_supported_p): Fix typo.
> 	* aarch64-tbl.h (THE): Remove.
> 	 (aarch64_feature_set aarch64_feature_the): Likewise.
> 
> gas/ChangeLog:
> 
> 	* testsuite/gas/aarch64/illegal-sysreg-8.l: Add tests for THE
> 	system registers.
> 	* testsuite/gas/aarch64/illegal-sysreg-8.s: Likewise.

Approved - please apply.

Cheers
   Nick