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Fix C++ UB from negating INT_MIN with macro shift INT_MIN

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This commit is contained in:
Rangi
2026-08-22 18:48:36 -04:00
parent 0888600cb7
commit e287ee2724
4 changed files with 11 additions and 1 deletions
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src/asm/macro.cpp
+1 -1
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@@ -72,7 +72,7 @@ void MacroArgs::shiftArgs(int32_t count) {
count > 0 && (static_cast<uint32_t>(count) > nbArgs || shift > nbArgs - count)) { count > 0 && (static_cast<uint32_t>(count) > nbArgs || shift > nbArgs - count)) {
warning(WARNING_MACRO_SHIFT, "Cannot shift macro arguments past their end"); warning(WARNING_MACRO_SHIFT, "Cannot shift macro arguments past their end");
shift = nbArgs; shift = nbArgs;
} else if (count < 0 && shift < static_cast<uint32_t>(-count)) { } else if (count < 0 && (count == INT32_MIN || shift < static_cast<uint32_t>(-count))) {
warning(WARNING_MACRO_SHIFT, "Cannot shift macro arguments past their beginning"); warning(WARNING_MACRO_SHIFT, "Cannot shift macro arguments past their beginning");
shift = 0; shift = 0;
} else { } else {
test/asm/shift-int-min.asm
+6
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@@ -0,0 +1,6 @@
MACRO m
println \1
shift $8000_0000 ; INT32_MIN
println \1
ENDM
m 1, 2, 3
test/asm/shift-int-min.err
+2
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@@ -0,0 +1,2 @@
warning: Cannot shift macro arguments past their beginning [-Wmacro-shift]
at shift-int-min.asm::m(3) <- shift-int-min.asm(6)
test/asm/shift-int-min.out
+2
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@@ -0,0 +1,2 @@
$1
$1