From d6ad07fdef94777bb512f072361706bcc743d51c Mon Sep 17 00:00:00 2001 From: Andreas Arnez Date: Fri, 19 Jan 2018 14:14:07 +0100 Subject: [PATCH] S390: Improve comments for s390-tdbregs test case This adds more explanation as to why the test case must be compiled with the -msoft-float option. It also documents the my_tbegin and my_tend functions. gdb/testsuite/ChangeLog: * gdb.arch/s390-tdbregs.c (my_tbegin): Add comment documenting the function. (my_tend): Likewise. * gdb.arch/s390-tdbregs.exp: Enhance comment; explain the rationale of avoiding FP- and vector instructions. --- gdb/testsuite/ChangeLog | 8 ++++++++ gdb/testsuite/gdb.arch/s390-tdbregs.c | 9 +++++++++ gdb/testsuite/gdb.arch/s390-tdbregs.exp | 6 ++++-- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index f3d31e70843..d510b794a95 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,11 @@ +2018-01-19 Andreas Arnez + + * gdb.arch/s390-tdbregs.c (my_tbegin): Add comment documenting the + function. + (my_tend): Likewise. + * gdb.arch/s390-tdbregs.exp: Enhance comment; explain the + rationale of avoiding FP- and vector instructions. + 2018-01-19 Ruslan Kabatsayev * gdb.arch/powerpc-d128-regs.exp: Replace expected "\[\t\]*" from diff --git a/gdb/testsuite/gdb.arch/s390-tdbregs.c b/gdb/testsuite/gdb.arch/s390-tdbregs.c index 2c768bb169e..57365aee1b0 100644 --- a/gdb/testsuite/gdb.arch/s390-tdbregs.c +++ b/gdb/testsuite/gdb.arch/s390-tdbregs.c @@ -17,6 +17,13 @@ #include +/* Start a transaction. To avoid the need for FPR save/restore, assume + that no FP- or vector registers are modified within the transaction. + Thus invoke TBEGIN with the "allow floating-point operation" flag set + to zero, which forces a transaction abort when hitting an FP- or vector + instruction. Also assume that TBEGIN will eventually succeed, so just + retry indefinitely. */ + static void my_tbegin () { @@ -28,6 +35,8 @@ my_tbegin () : "cc", "memory" ); } +/* End a transaction. */ + static void my_tend () { diff --git a/gdb/testsuite/gdb.arch/s390-tdbregs.exp b/gdb/testsuite/gdb.arch/s390-tdbregs.exp index 47d9d380cac..e454feb9d94 100644 --- a/gdb/testsuite/gdb.arch/s390-tdbregs.exp +++ b/gdb/testsuite/gdb.arch/s390-tdbregs.exp @@ -26,8 +26,10 @@ if { ![istarget s390-*-*] && ![istarget s390x-*-* ] } { standard_testfile .c -# Use soft float, so the compiler doesn't use floating-point or vector -# instructions. +# The test case assumes that no FP- or vector instructions occur within +# the transaction. Thus tell the compiler to use soft float, so it +# doesn't emit them. Some GCC versions may otherwise do so, and an +# endless loop would result. if { [prepare_for_testing "failed to prepare" $testfile $srcfile \ [list "debug" "additional_flags=-msoft-float"]] } { return -1 -- 2.30.2