[nvptx] Improve help description of misa and mptx

Currently we have:
...
$ gcc --target-help 2>&1 | egrep "misa|mptx"
  -misa=                      Specify the version of the ptx ISA to use.
  -mptx=                      Specify the version of the ptx version to use.
  Known PTX ISA versions (for use with the -misa= option):
  Known PTX versions (for use with the -mptx= option):
...

As reported in PR104818, the "version of the ptx version" doesn't make much
sense.

Furthermore, the description of misa (and 'Known ISA versions') is misleading
because it does not specify the version of the PTX ISA, but rather the PTX ISA
target architecture.

Fix this by printing instead:
...
$ gcc --target-help 2>&1 | egrep "misa|mptx"
  -misa=                      Specify the PTX ISA target architecture to use.
  -mptx=                      Specify the PTX ISA version to use.
  Known PTX ISA target architectures (for use with the -misa= option):
  Known PTX ISA versions (for use with the -mptx= option):
...

Tested on nvptx.

gcc/ChangeLog:

2022-03-28  Tom de Vries  <tdevries@suse.de>

	PR target/104818
	* config/nvptx/gen-opt.sh (ptx_isa): Improve help text.
	* config/nvptx/nvptx-gen.opt: Regenerate.
	* config/nvptx/nvptx.opt (misa, mptx, ptx_version): Improve help text.
	* config/nvptx/t-nvptx (s-nvptx-gen-opt): Add missing dependency on
	gen-opt.sh.

4 files changed, 7 insertions, 6 deletions

diff --git a/gcc/config/nvptx/gen-opt.sh b/gcc/config/nvptx/gen-opt.sh
index 5248ed2..ba04889 100644
--- a/gcc/config/nvptx/gen-opt.sh
+++ b/gcc/config/nvptx/gen-opt.sh
@@ -44,7 +44,7 @@ echo
 cat <<EOF
 Enum
 Name(ptx_isa) Type(int)
-Known PTX ISA versions (for use with the -misa= option):
+Known PTX ISA target architectures (for use with the -misa= option):
 EOF
 
 # Separator.
diff --git a/gcc/config/nvptx/nvptx-gen.opt b/gcc/config/nvptx/nvptx-gen.opt
index b6d433e..0f5889e 100644
--- a/gcc/config/nvptx/nvptx-gen.opt
+++ b/gcc/config/nvptx/nvptx-gen.opt
@@ -21,7 +21,7 @@
 
 Enum
 Name(ptx_isa) Type(int)
-Known PTX ISA versions (for use with the -misa= option):
+Known PTX ISA target architectures (for use with the -misa= option):
 
 EnumValue
 Enum(ptx_isa) String(sm_30) Value(PTX_ISA_SM30)
diff --git a/gcc/config/nvptx/nvptx.opt b/gcc/config/nvptx/nvptx.opt
index 11288d1..1f684ed 100644
--- a/gcc/config/nvptx/nvptx.opt
+++ b/gcc/config/nvptx/nvptx.opt
@@ -54,11 +54,11 @@ Generate code for OpenMP offloading: enables -msoft-stack and -muniform-simt.
 ; Default needs to be in sync with default in ASM_SPEC in nvptx.h.
 misa=
 Target RejectNegative ToLower Joined Enum(ptx_isa) Var(ptx_isa_option) Init(PTX_ISA_SM30)
-Specify the version of the ptx ISA to use.
+Specify the PTX ISA target architecture to use.
 
 Enum
 Name(ptx_version) Type(int)
-Known PTX versions (for use with the -mptx= option):
+Known PTX ISA versions (for use with the -mptx= option):
 
 EnumValue
 Enum(ptx_version) String(3.1) Value(PTX_VERSION_3_1)
@@ -77,7 +77,7 @@ Enum(ptx_version) String(_) Value(PTX_VERSION_default)
 
 mptx=
 Target RejectNegative ToLower Joined Enum(ptx_version) Var(ptx_version_option)
-Specify the version of the ptx version to use.
+Specify the PTX ISA version to use.
 
 minit-regs=
 Target Var(nvptx_init_regs) IntegerRange(0, 3) Joined UInteger Init(3)
diff --git a/gcc/config/nvptx/t-nvptx b/gcc/config/nvptx/t-nvptx
index b63c4a5..2b68149 100644
--- a/gcc/config/nvptx/t-nvptx
+++ b/gcc/config/nvptx/t-nvptx
@@ -23,7 +23,8 @@ s-nvptx-gen-h: $(srcdir)/config/nvptx/nvptx-sm.def
 	$(STAMP) s-nvptx-gen-h
 
 $(srcdir)/config/nvptx/nvptx-gen.opt: s-nvptx-gen-opt; @true
-s-nvptx-gen-opt: $(srcdir)/config/nvptx/nvptx-sm.def
+s-nvptx-gen-opt: $(srcdir)/config/nvptx/nvptx-sm.def \
+  $(srcdir)/config/nvptx/gen-opt.sh
 	$(SHELL) $(srcdir)/config/nvptx/gen-opt.sh "$(srcdir)/config/nvptx" \
 	  > tmp-nvptx-gen.opt
 	$(SHELL) $(srcdir)/../move-if-change \