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Andrew Burgess c67f2e1518 gdb: Ensure compiler doesn't optimise variable out in test
In the test gdb.base/funcargs.exp, there's this function:

    void recurse (SVAL a, int depth)
    {
      a.s = a.i = a.l = --depth;
      if (depth == 0)
        hitbottom ();
      else
        recurse (a, depth);
    }

The test script places a breakpoint in hitbottom, and runs the
executable which calls recurse with an initial depth of 4.

When GDB hits the breakpoint in hitbottom the testscript performs a
backtrace, and examines 'a' at each level.

The problem is that 'a' is not live after either the call to
'hitbottom' or the call to 'recurse', and as a result the test fails.

In the particular case I was looking at GCC for RISC-V 32-bit, the
variable 'a' is on the stack and GCC selects the register $ra (the
return address register) to hold the pointer to 'a'.  This is fine,
because, by the time the $ra register is needed to hold a return
address (calling hitbottom or recurse) then 'a' is dead.

In this patch I propose that a use of 'a' is added after the calls to
hitbottom and recurse, this should cause the compiler to keep 'a'
around, which should ensure GDB can find it.

gdb/testsuite/ChangeLog:

	* gdb.base/funcargs.c (use_a): New function.
	(recurse): Call use_a.
2018-08-30 16:33:49 +01:00
bfd Automatic date update in version.in 2018-08-30 00:01:03 +00:00
binutils Treat SHT_FINI_ARRAY and SHT_PREINIT_ARRAY as relocatable sections 2018-08-30 08:03:34 -07:00
config
contrib
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elfcpp [MIPS] Add Loongson 2K1000 proccessor support. 2018-08-29 20:55:25 +08:00
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gas Treat SHT_FINI_ARRAY and SHT_PREINIT_ARRAY as relocatable sections 2018-08-30 08:03:34 -07:00
gdb gdb: Ensure compiler doesn't optimise variable out in test 2018-08-30 16:33:49 +01:00
gold [MIPS] Add Loongson 2K1000 proccessor support. 2018-08-29 20:55:25 +08:00
gprof
include [MIPS] Add Loongson 2K1000 proccessor support. 2018-08-29 20:55:25 +08:00
intl
ld [MIPS] Add Loongson 2K1000 proccessor support. 2018-08-29 20:55:25 +08:00
libdecnumber
libiberty
opcodes sparc/leon: add support for partial write psr instruction 2018-08-29 20:52:28 +02:00
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