[binutils-gdb] [gdb/testsuite] Allow some tests in gdb.base/store.exp to be unsupported

[binutils-gdb] [gdb/testsuite] Allow some tests in gdb.base/store.exp to be unsupported

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=25e5c20918a0ec69e37c1987db52062b0eab7194

commit 25e5c20918a0ec69e37c1987db52062b0eab7194
Author: Tom de Vries <tdevries@suse.de>
Date:   Thu Sep 12 22:36:37 2019 +0200

    [gdb/testsuite] Allow some tests in gdb.base/store.exp to be unsupported
    
    The test-case gdb.base/store.exp fails with gcc 7.4.0:
    ...
    nr of unexpected failures        27
    ...
    
    The first FAIL:
    ...
    110       l = add_float (l, r);
    (gdb) PASS: gdb.base/store.exp: continue to wack_float
    print l
    $21 = <optimized out>
    FAIL: gdb.base/store.exp: var float l; print old l, expecting -1
    ...
    relates to this bit in the test-case (compiled at -O0):
    ...
       106  float
       107  wack_float (register float u, register float v)
       108  {
       109    register float l = u, r = v;
       110    l = add_float (l, r);
       111    return l + r;
       112  }
    ...
    and it expects to be able to read and modify variable l before executing line
    110, but it already fails to read the value, because l has no DW_AT_location
    attribute in the debug info.
    
    Variable l is declared with the register keyword, and GCC implements the
    register keyword at -O0 like so:
    ...
    the compiler allocates distinct stack memory for all variables that do not
    have the register storage-class specifier; if register is specified, the
    variable may have a shorter lifespan than the code would indicate and may
    never be placed in memory.
    ...
    
    The fact that l has no DW_AT_location attribute, matches with the documented
    "variable may have a shorter lifespan that code would indicate", (though it
    is the most extreme case of it) so the gcc behaviour is valid.  We can of
    course improve gcc to generate better debuginfo (filed gcc PR91611), but
    this not a wrong-debug problem.
    
    [ The test-case passes with gcc 4.2.1, but for the failing test discussed
    above, it passes simply because it doesn't store l in a register. ]
    
    With the debug info missing for l, reading and setting l is unsupported, so
    fix the FAIL by marking the test UNSUPPORTED instead.
    
    Tested on x86_64-linux.
    
    gdb/testsuite/ChangeLog:
    
    2019-09-12  Tom de Vries  <tdevries@suse.de>
    
    	* gdb.base/store.exp: Allow register variables to be optimized out at
    	-O0.

Diff:
---
 gdb/testsuite/ChangeLog          |  5 ++++
 gdb/testsuite/gdb.base/store.exp | 65 +++++++++++++++++++++++++++-------------
 2 files changed, 50 insertions(+), 20 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index bf3fcc7..7352e9f 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-09-12  Tom de Vries  <tdevries@suse.de>
+
+	* gdb.base/store.exp: Allow register variables to be optimized out at
+	-O0.
+
 2019-09-12  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
 
 	* gdb.ada/rdv_wait.exp: Update to new task names.
diff --git a/gdb/testsuite/gdb.base/store.exp b/gdb/testsuite/gdb.base/store.exp
index c5a7584..9c19ce1 100644
--- a/gdb/testsuite/gdb.base/store.exp
+++ b/gdb/testsuite/gdb.base/store.exp
@@ -55,18 +55,29 @@ proc check_set { t l r new add } {
 	}
     }
 
-    gdb_test "print l" " = ${l}" \
-	"${prefix}; print old l, expecting ${l}"
-    gdb_test "print r" " = ${r}" \
-	"${prefix}; print old r, expecting ${r}"
-    gdb_test_no_output "set variable l = 4" \
-	"${prefix}; setting l to 4"
-    gdb_test "print l" " = ${new}" \
-	"${prefix}; print new l, expecting ${new}"
-    gdb_test "next" "return l \\+ r;" \
-	"${prefix}; next over add call"
-    gdb_test "print l" " = ${add}" \
-	"${prefix}; print incremented l, expecting ${add}"
+    set supported 1
+    set test "${prefix}; print old l, expecting ${l}"
+    gdb_test_multiple "print l" "$test"  {
+	-re " = <optimized out>\r\n$gdb_prompt $" {
+	    unsupported $test
+	    set supported 0
+	}
+	-re " = ${l}\r\n$gdb_prompt $" {
+	    pass $test
+	}
+    }
+    if { $supported } {
+	gdb_test "print r" " = ${r}" \
+	    "${prefix}; print old r, expecting ${r}"
+	gdb_test_no_output "set variable l = 4" \
+	    "${prefix}; setting l to 4"
+	gdb_test "print l" " = ${new}" \
+	    "${prefix}; print new l, expecting ${new}"
+	gdb_test "next" "return l \\+ r;" \
+	    "${prefix}; next over add call"
+	gdb_test "print l" " = ${add}" \
+	    "${prefix}; print incremented l, expecting ${add}"
+    }
 }
 
 check_set "charest" "-1 .*" "-2 .*" "4 ..004." "2 ..002."
@@ -81,20 +92,34 @@ check_set "doublest" "-1" "-2" "4" "2"
 #
 
 proc up_set { t l r new } {
+    global gdb_prompt
+
     set prefix "upvar ${t} l"
     gdb_test "tbreak add_${t}"
     gdb_test "continue" "return u . v;" \
 	"continue to add_${t}"
     gdb_test "up" "l = add_${t} .l, r.;" \
 	"${prefix}; up"
-    gdb_test "print l" " = ${l}" \
-	"${prefix}; print old l, expecting ${l}"
-    gdb_test "print r" " = ${r}" \
-	"${prefix}; print old r, expecting ${r}"
-    gdb_test_no_output "set variable l = 4" \
-	"${prefix}; set l to 4"
-    gdb_test "print l" " = ${new}" \
-	"${prefix}; print new l, expecting ${new}"
+
+    set supported 1
+    set test "${prefix}; print old l, expecting ${l}"
+    gdb_test_multiple "print l" "$test"  {
+	-re " = <optimized out>\r\n$gdb_prompt $" {
+	    unsupported $test
+	    set supported 0
+	}
+	-re " = ${l}\r\n$gdb_prompt $" {
+	    pass $test
+	}
+    }
+    if { $supported } {
+	gdb_test "print r" " = ${r}" \
+	    "${prefix}; print old r, expecting ${r}"
+	gdb_test_no_output "set variable l = 4" \
+	    "${prefix}; set l to 4"
+	gdb_test "print l" " = ${new}" \
+	    "${prefix}; print new l, expecting ${new}"
+    }
 }
 
 up_set "charest" "-1 .*" "-2 .*" "4 ..004."