[committed] Fix missing mode on a few unspec/unspec_volatile operands

This is fix for a minor problem Jivan and I found while testing the ext-dce work originally from Joern.

The ext-dce pass will transform zero/sign extensions into subreg accesses when
the upper bits are actually unused.  So it's more likely with the ext-dce work
to get a sequence like this prior to combine:

>
>> (insn 10 9 11 2 (set (reg:SI 144)
>>         (unspec_volatile [
>>                 (const_int 0 [0])
>>             ] UNSPECV_FRFLAGS)) "j.c":11:3 discrim 1 362 {riscv_frflags}
>>      (nil))
>> (insn 11 10 55 2 (set (reg:DI 140 [ _12 ])
>>         (subreg:DI (reg:SI 144) 0)) "j.c":11:3 discrim 1 206 {*movdi_64bit}
>>      (expr_list:REG_DEAD (reg:SI 144)
>>         (nil)))

When we try to combine insn 10->11 we'll ultimately call simplify_subreg with
something like

(subreg:DI (unspec_volatile [...]) 0)

Note the lack of a mode on the unspec_volatile.  That in turn will cause
simplify_subreg to trigger an assertion.

The modeless unspec is generated by the RISC-V backend and the more I've
pondered this issue over the last few days the more I'm convinced it's a
backend bug.  Basically if the LHS of the set has a mode, then the RHS of the
set should have a mode as well.

I've audited the various backends and only found a few problems which are fixed
by this patch.  I've tested the relevant ports in my tester.  c6x, sh, mips and
s390[x].

There are other patterns that are potentially problematical in various ports.
They have a REG destination and an UNSPEC source, but the REG has no mode in
the pattern.  Since it wasn't clear what mode to give the UNSPEC, I left those
alone.

gcc/

	* config/c6x/c6x.md (mvilc): Add mode to UNSPEC source.
	* config/mips/mips.md (rdhwr_synci_step_<mode>): Likewise.
	* config/riscv/riscv.md (riscv_frcsr, riscv_frflags): Likewise.
	* config/s390/s390.md (@split_stack_call<mode>): Likewise.
	(@split_stack_cond_call<mode>): Likewise.
	* config/sh/sh.md (sp_switch_1): Likewise.

5 files changed, 11 insertions, 11 deletions

diff --git a/gcc/config/c6x/c6x.md b/gcc/config/c6x/c6x.md
index 88b9291..906fdb3 100644
--- a/gcc/config/c6x/c6x.md
+++ b/gcc/config/c6x/c6x.md
@@ -1440,7 +1440,7 @@
 
 (define_insn "mvilc"
   [(set (reg:SI REG_ILC)
-	(unspec [(match_operand:SI 0 "register_operand" "a,b")] UNSPEC_MVILC))]
+	(unspec:SI [(match_operand:SI 0 "register_operand" "a,b")] UNSPEC_MVILC))]
   "TARGET_INSNS_64PLUS"
   "%|%.\\tmvc\\t%$\\t%0, ILC"
   [(set_attr "predicable" "no")
diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index a254547..0666310 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -5732,7 +5732,7 @@
 
 (define_insn "rdhwr_synci_step_<mode>"
   [(set (match_operand:P 0 "register_operand" "=d")
-        (unspec_volatile [(const_int 1)]
+        (unspec_volatile:P [(const_int 1)]
         UNSPEC_RDHWR))]
   "ISA_HAS_SYNCI"
   "rdhwr\t%0,$1")
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 8f28e8e..1522b0b 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -3301,7 +3301,7 @@
 
 (define_insn "riscv_frcsr"
   [(set (match_operand:SI 0 "register_operand" "=r")
-	(unspec_volatile [(const_int 0)] UNSPECV_FRCSR))]
+	(unspec_volatile:SI [(const_int 0)] UNSPECV_FRCSR))]
   "TARGET_HARD_FLOAT || TARGET_ZFINX"
   "frcsr\t%0"
   [(set_attr "type" "fmove")])
@@ -3314,7 +3314,7 @@
 
 (define_insn "riscv_frflags"
   [(set (match_operand:SI 0 "register_operand" "=r")
-	(unspec_volatile [(const_int 0)] UNSPECV_FRFLAGS))]
+	(unspec_volatile:SI [(const_int 0)] UNSPECV_FRFLAGS))]
   "TARGET_HARD_FLOAT || TARGET_ZFINX"
   "frflags\t%0"
   [(set_attr "type" "fmove")])
diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md
index 4bdb679..bc740a7 100644
--- a/gcc/config/s390/s390.md
+++ b/gcc/config/s390/s390.md
@@ -12252,9 +12252,9 @@
 
 (define_insn "@split_stack_call<mode>"
   [(set (pc) (label_ref (match_operand 2 "" "")))     ; call done label
-   (set (reg:P 1) (unspec_volatile [(match_operand 0 "bras_sym_operand" "X")
-				    (reg:P 1)]
-				   UNSPECV_SPLIT_STACK_CALL))
+   (set (reg:P 1) (unspec_volatile:P [(match_operand 0 "bras_sym_operand" "X")
+				      (reg:P 1)]
+				     UNSPECV_SPLIT_STACK_CALL))
    (use (label_ref (match_operand 1 "" "X")))         ; parm block label
    (use (match_operand 3 "const_int_operand" "X"))    ; frame size
    (use (match_operand 4 "const_int_operand" "X"))]   ; arg size
@@ -12274,9 +12274,9 @@
 	  (match_operand 5 "" "")                     ; condition
 	  (label_ref (match_operand 2 "" ""))         ; call done label
 	  (pc)))
-   (set (reg:P 1) (unspec_volatile [(match_operand 0 "bras_sym_operand" "X")
-				    (reg:P 1)]
-				   UNSPECV_SPLIT_STACK_CALL))
+   (set (reg:P 1) (unspec_volatile:P [(match_operand 0 "bras_sym_operand" "X")
+				      (reg:P 1)]
+				     UNSPECV_SPLIT_STACK_CALL))
    (use (label_ref (match_operand 1 "" "X")))         ; parm block label
    (use (match_operand 3 "const_int_operand" "X"))    ; frame size
    (use (match_operand 4 "const_int_operand" "X"))]   ; arg size
diff --git a/gcc/config/sh/sh.md b/gcc/config/sh/sh.md
index 193f40d..8321d9f 100644
--- a/gcc/config/sh/sh.md
+++ b/gcc/config/sh/sh.md
@@ -10936,7 +10936,7 @@
 
 ;; Switch to a new stack with its address in sp_switch (a SYMBOL_REF).
 (define_insn "sp_switch_1"
-  [(set (reg:SI SP_REG) (unspec_volatile [(match_operand:SI 0 "" "")]
+  [(set (reg:SI SP_REG) (unspec_volatile:SI [(match_operand:SI 0 "" "")]
     UNSPECV_SP_SWITCH_B))]
   "TARGET_SH1"
 {