[gcc r14-3873] nvptx: stack size limits are relevant for execution only

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:56004123ab74193d88ad297877fa4e2a0d7ef5b1

commit r14-3873-g56004123ab74193d88ad297877fa4e2a0d7ef5b1
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Tue Nov 8 12:10:03 2022 +0100

    nvptx: stack size limits are relevant for execution only
    
    For non-'dg-do run' test cases, that means: big 'dg-require-stack-size' need
    not be UNSUPPORTED (and indeed now do all PASS), 'dg-add-options stack_size'
    need not define (and thus limit) 'STACK_SIZE' (and still do all PASS).
    
    Re "Find 'dg-do-what' in an outer frame", currently (sources not completely
    clean, though), we've got:
    
        $ git grep -F 'check_effective_target_stack_size: found dg-do-what at level ' -- build-gcc/\*.log | sort | uniq -c
              6 build-gcc/gcc/testsuite/gcc/gcc.log:check_effective_target_stack_size: found dg-do-what at level 2
            267 build-gcc/gcc/testsuite/gcc/gcc.log:check_effective_target_stack_size: found dg-do-what at level 3
            239 build-gcc/gcc/testsuite/gcc/gcc.log:check_effective_target_stack_size: found dg-do-what at level 4
    
            gcc/testsuite/
            * lib/target-supports.exp (check_effective_target_stack_size): For
            nvptx target, stack size limits are relevant for execution only.
            gcc/
            * doc/sourcebuild.texi (stack_size): Update.

Diff:
---
 gcc/doc/sourcebuild.texi              |  4 ++++
 gcc/testsuite/lib/target-supports.exp | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index de1aa8c2dbab..8bf701461ec6 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -2932,6 +2932,10 @@ Target has limited stack size.  The stack size limit can be obtained using the
 STACK_SIZE macro defined by @ref{stack_size_ao,,@code{dg-add-options} feature
 @code{stack_size}}.
 
+Note that for certain targets, stack size limits are relevant for
+execution only, and therefore considered only if @code{dg-do run} is
+in effect, otherwise unlimited.
+
 @item static
 Target supports @option{-static}.
 
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 0ea8bcb24e1b..1080a5cfc443 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -649,6 +649,22 @@ proc check_effective_target_trampolines { } {
 # Return 1 if target has limited stack size.
 
 proc check_effective_target_stack_size { } {
+    # For nvptx target, stack size limits are relevant for execution only.
+    if { [istarget nvptx-*-*] } {
+	# Find 'dg-do-what' in an outer frame.
+	set level 1
+	while true {
+	    upvar $level dg-do-what dg-do-what
+	    if [info exists dg-do-what] then break
+	    incr level
+	}
+	verbose "check_effective_target_stack_size: found dg-do-what at level $level" 2
+
+	if { ![string equal [lindex ${dg-do-what} 0] run] } {
+	    return 0
+	}
+    }
+
     if [target_info exists gcc,stack_size] {
 	return 1
     }