nvptx: bump default to PTX 4.1

gcc/ChangeLog:

	* config/nvptx/nvptx-opts.h (ptx_version): Change PTX_VERSION_3_1 to
	PTX_VERSION_4_1.
	* config/nvptx/nvptx.c (nvptx_file_start): Bump minimum PTX version
	to 4.1.
	* config/nvptx/nvptx.opt (ptx_version): Add 4.1. Change default.
	doc/invoke.texi: -mptx default is now 4.1.

diff --git a/gcc/config/nvptx/nvptx-opts.h b/gcc/config/nvptx/nvptx-opts.h
index 7b6ecd42fed..c7fcf1c8cd4 100644
--- a/gcc/config/nvptx/nvptx-opts.h
+++ b/gcc/config/nvptx/nvptx-opts.h
@@ -31,7 +31,7 @@ enum ptx_isa
 
 enum ptx_version
 {
-  PTX_VERSION_3_1,
+  PTX_VERSION_4_1,
   PTX_VERSION_6_3,
   PTX_VERSION_7_0
 };
diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index ff44d9fdbef..9bc26d7de0c 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -5409,7 +5409,7 @@ nvptx_file_start (void)
   else if (TARGET_PTX_6_3)
     fputs ("\t.version\t6.3\n", asm_out_file);
   else
-    fputs ("\t.version\t3.1\n", asm_out_file);
+    fputs ("\t.version\t4.1\n", asm_out_file);
   if (TARGET_SM80)
     fputs ("\t.target\tsm_80\n", asm_out_file);
   else if (TARGET_SM75)
diff --git a/gcc/config/nvptx/nvptx.opt b/gcc/config/nvptx/nvptx.opt
index 1d88ef18d04..9e6a6a7fbff 100644
--- a/gcc/config/nvptx/nvptx.opt
+++ b/gcc/config/nvptx/nvptx.opt
@@ -79,8 +79,12 @@ Enum
 Name(ptx_version) Type(int)
 Known PTX versions (for use with the -mptx= option):
 
+; Keep 3.1 for backwards compatibility only
 EnumValue
-Enum(ptx_version) String(3.1) Value(PTX_VERSION_3_1)
+Enum(ptx_version) String(3.1) Value(PTX_VERSION_4_1)
+
+EnumValue
+Enum(ptx_version) String(4.1) Value(PTX_VERSION_4_1)
 
 EnumValue
 Enum(ptx_version) String(6.3) Value(PTX_VERSION_6_3)
@@ -89,5 +93,5 @@ EnumValue
 Enum(ptx_version) String(7.0) Value(PTX_VERSION_7_0)
 
 mptx=
-Target RejectNegative ToLower Joined Enum(ptx_version) Var(ptx_version_option) Init(PTX_VERSION_3_1)
+Target RejectNegative ToLower Joined Enum(ptx_version) Var(ptx_version_option) Init(PTX_VERSION_4_1)
 Specify the version of the ptx version to use.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 37836a7d614..92f0da62a2b 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27056,8 +27056,8 @@ strings must be lower-case.  Valid ISA strings include @samp{sm_30} and
 @item -mptx=@var{version-string}
 @opindex mptx
 Generate code for given the specified PTX version (e.g.@: @samp{6.3}).
-Valid version strings include @samp{3.1} and @samp{6.3}.  The default PTX
-version is 3.1.
+Valid version strings include @samp{4.1} and @samp{6.3}.  The default PTX
+version is 4.1.
 
 @item -mmainkernel
 @opindex mmainkernel