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Diffstat (limited to 'tests/cases/gepaddoverflow.ll')
| -rw-r--r-- | tests/cases/gepaddoverflow.ll | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/tests/cases/gepaddoverflow.ll b/tests/cases/gepaddoverflow.ll new file mode 100644 index 00000000..11246c1d --- /dev/null +++ b/tests/cases/gepaddoverflow.ll @@ -0,0 +1,37 @@ +; ModuleID = 'new.o' +target datalayout = "e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-p:32:32:32-v128:32:32" +target triple = "le32-unknown-nacl" + +declare i32 @printf(i8* noalias, ...) nounwind + +@x = common global [4194304 x i8] zeroinitializer, align 4 +@.str = private constant [6 x i8] c"*%d*\0A\00", align 1 + +define i8* @test_gep(i32 %y) nounwind readnone { + ; JavaScript uses double precision 64-bit floating point values, with + ; a 53 bit mantissa. The maximum precisely representable integer is + ; 9007199254740992. A number close to that limit is constructed here + ; for the constant part of the getelementptr instruction: + ; 4194304 * 2147483647 == 9007199250546688 == 9007199254740992 - 4194304 + ; If that number appears in JavaScript source instead of being properly + ; limited to 32 bits, the %y parameter can be used to exceed the maximum + ; precisely representable integer, and make the computation inexact. + %test_res = getelementptr [4194304 x i8]* @x, i32 2147483647, i32 %y + ret i8* %test_res +} + +define i32 @main() { + %res_0 = call i8* (i32)* @test_gep(i32 1000000000) + %res_1 = call i8* (i32)* @test_gep(i32 1000000001) + %res_0_i = ptrtoint i8* %res_0 to i32 + %res_1_i = ptrtoint i8* %res_1 to i32 + + ; If getelementptr limited the constant part of the offset to 32 bits, + ; result will be 1. Otherwise, it cannot be 1 because the large numbers in + ; the calculation cannot be accurately represented by floating point math. + %res_diff = sub i32 %res_1_i, %res_0_i + %printf_res = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([6 x i8]* @.str, i32 0, i32 0), i32 %res_diff) + + ret i32 0 +} + |