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gas: fix overflow diagnostics
While the logic in fixup_segment() so far was off by 1 for fixups
dealing with quantities without known signedness, thus failing to report
an overflow when e.g. a byte-sized resulting value is -0x100, the logic
in emit_expr_with_reloc() reported an overflow even on large negative
values when the respective positive ones would not be warned
about, and when fixup_segment() wouldn't do so either. Such diagnostics
all ought to follow a similar pattern of what value range is acceptable.
(If expressions' X_unsigned was reliably set, emit_expr_with_reloc()'s
checking might make sense to tighten based on that flag.)
Note that with commit 80aab57939 ("Changes to let cons handle bignums
like general expressions") having added handling of nbytes >
sizeof(valueT) in the O_constant case, converting to O_big, the setting
to zero of "hibit" had become dead. With "hibit" no longer used, this
code now gets dropped altogether. But additionally a respective know()
gets inserted.
This commit is contained in:
Jan Beulich
parent
b80d447580
commit
4504a63467
@ -1,3 +1,13 @@
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2021-06-16 Jan Beulich <jbeulich@suse.com>
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* read.c (emit_expr_with_reloc): Adjust overflow check. Drop
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hibit local variable.
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* write.c (fixup_segment): Differentiate signed and non-signed
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relocs in overflow check.
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* testsuite/gas/all/overflow.s,
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testsuite/gas/all/overflow.l: New.
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* testsuite/gas/all/gas.exp: Run new test.
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2021-06-15 Jan Beulich <jbeulich@suse.com>
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* config/tc-i386.c (md_show_usage): Split ELF and PE/COFF parts
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11
gas/read.c
11
gas/read.c
@ -4505,24 +4505,19 @@ emit_expr_with_reloc (expressionS *exp,
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valueT get;
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valueT use;
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valueT mask;
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valueT hibit;
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valueT unmask;
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/* JF << of >= number of bits in the object is undefined. In
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particular SPARC (Sun 4) has problems. */
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if (nbytes >= sizeof (valueT))
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{
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know (nbytes == sizeof (valueT));
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mask = 0;
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if (nbytes > sizeof (valueT))
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hibit = 0;
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else
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hibit = (valueT) 1 << (nbytes * BITS_PER_CHAR - 1);
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}
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else
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{
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/* Don't store these bits. */
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mask = ~(valueT) 0 << (BITS_PER_CHAR * nbytes);
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hibit = (valueT) 1 << (nbytes * BITS_PER_CHAR - 1);
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}
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unmask = ~mask; /* Do store these bits. */
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@ -4534,9 +4529,7 @@ emit_expr_with_reloc (expressionS *exp,
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get = exp->X_add_number;
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use = get & unmask;
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if ((get & mask) != 0
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&& ((get & mask) != mask
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|| (get & hibit) == 0))
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if ((get & mask) != 0 && (-get & mask) != 0)
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{
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/* Leading bits contain both 0s & 1s. */
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as_warn (_("value 0x%" BFD_VMA_FMT "x truncated to 0x%" BFD_VMA_FMT "x"),
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@ -372,6 +372,27 @@ switch -glob $target_triplet {
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}
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}
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# Various targets use too custom handling to be able to sensibly create
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# common expecations for this test. Also .equ works differently on some
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# targets.
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if { ![istarget avr-*-*]
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&& ![istarget bfin-*-*]
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&& ![istarget cris*-*-*]
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&& ![istarget dlx-*-*]
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&& ![istarget hppa*-*-*]
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&& ![istarget m68k-*-*]
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&& ![istarget nios2-*-*]
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&& ![istarget pj-*-*]
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&& ![istarget sh*-*-*]
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&& ![istarget *c4x-*-*]
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&& ![istarget *c54x-*-*]
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&& ![istarget *c6x-*-*]
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&& ![istarget z80-*-*] } then {
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# Some further targets' custom handling fails to recognize the overflows.
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setup_xfail "crx-*-*" "h8300-*-*" "mcore-*-*" "mn10200-*-*" "mn10300-*-*" "msp430-*-*" "ns32k-*-*"
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run_list_test "overflow"
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}
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if { ([istarget "i*86-*-*pe*"] && ![istarget "i*86-*-openbsd*"]) \
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|| [istarget "i*86-*-cygwin*"] \
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|| [istarget "i*86-*-mingw32*"] } {
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9
gas/testsuite/gas/all/overflow.l
Normal file
9
gas/testsuite/gas/all/overflow.l
Normal file
@ -0,0 +1,9 @@
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.*: Assembler messages:
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.*:5: Warning: .* (0x)?100 truncated to (0x)?0
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.*:6: Warning: .* (0x)?101 truncated to (0x)?1
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.*:11: Warning: .* (0x)?f+00 truncated to (0x)?0
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.*:12: Warning: .* (0x)?f+eff truncated to (0x)?ff
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.*:17: Error: .* (256|(0x)?100) too large .*
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.*:18: Error: .* (257|(0x)?101) too large .*
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.*:23: Error: .* (0x)?f+00 too large .*
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.*:24: Error: .* (0x)?f+eff too large .*
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26
gas/testsuite/gas/all/overflow.s
Normal file
26
gas/testsuite/gas/all/overflow.s
Normal file
@ -0,0 +1,26 @@
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.data
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.dc.b +0x80
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.dc.b +0x81
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.dc.b +0xff
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.dc.b +0x100
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.dc.b +0x101
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.dc.b -0x80
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.dc.b -0x81
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.dc.b -0xff
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.dc.b -0x100
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.dc.b -0x101
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.dc.b zero+0x80
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.dc.b zero+0x81
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.dc.b zero+0xff
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.dc.b zero+0x100
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.dc.b zero+0x101
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.dc.b zero-0x80
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.dc.b zero-0x81
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.dc.b zero-0xff
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.dc.b zero-0x100
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.dc.b zero-0x101
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.equ zero, 0
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@ -1107,7 +1107,10 @@ fixup_segment (fixS *fixP, segT this_segment)
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mask = 0;
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mask--; /* Set all bits to one. */
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mask <<= fixP->fx_size * 8 - (fixP->fx_signed ? 1 : 0);
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if ((add_number & mask) != 0 && (add_number & mask) != mask)
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if ((add_number & mask) != 0
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&& (fixP->fx_signed
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? (add_number & mask) != mask
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: (-add_number & mask) != 0))
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{
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char buf[50], buf2[50];
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bfd_sprintf_vma (stdoutput, buf, fragP->fr_address + fixP->fx_where);
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