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Fix __builtin_*_overflow when out-param isn't constexpr 

As brought up on cfe-commits[1], r334650 causes the dependency of the
out parameter to the __builtin_*_overflow functions to be ignored. The result
was a usage that was otherwise constexpr (both operands to the operation were
constexpr) would be evaluated, but the out parameter wouldn't be modified, so
it would still be 'undef'.

This patch correctly handles the return value of handleAssignment to ensure that
this value is properly considered/evaluated.

[1] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180702/233667.html


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@336364 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Erich Keane 2018-07-05 15:52:58 +00:00
parent aa316d40ec
commit feb79d981f
2 changed files with 18 additions and 1 deletions
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3
lib/AST/ExprConstant.cpp
View File

@ -8346,7 +8346,8 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
}
APValue APV{Result};
handleAssignment(Info, E, ResultLValue, ResultType, APV);
if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
return false;
return Success(DidOverflow, E);
}
}

16
test/CodeGenCXX/builtins.cpp
View File

@ -30,3 +30,19 @@ long y = __builtin_abs(-2l);
extern const char char_memchr_arg[32];
char *memchr_result = __builtin_char_memchr(char_memchr_arg, 123, 32);
// CHECK: call i8* @memchr(i8* getelementptr inbounds ([32 x i8], [32 x i8]* @char_memchr_arg, i32 0, i32 0), i32 123, i64 32)
int constexpr_overflow_result() {
constexpr int x = 1;
// CHECK: alloca i32
constexpr int y = 2;
// CHECK: alloca i32
int z;
// CHECK: [[Z:%.+]] = alloca i32
__builtin_sadd_overflow(x, y, &z);
return z;
// CHECK: [[RET_PTR:%.+]] = extractvalue { i32, i1 } %0, 0
// CHECK: store i32 [[RET_PTR]], i32* [[Z]]
// CHECK: [[RET_VAL:%.+]] = load i32, i32* [[Z]]
// CHECK: ret i32 [[RET_VAL]]
}