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[v3,02/22] host-utils: fix missing zero-extension in divs128

Message ID 20210910112624.72748-3-luis.pires@eldorado.org.br
State New
Headers show
Series target/ppc: DFP instructions using decodetree | expand

Commit Message

Luis Fernando Fujita Pires Sept. 10, 2021, 11:26 a.m. UTC 
*plow (lower 64 bits of the dividend) is passed into divs128() as
a signed 64-bit integer. When building an __int128_t from it, it
must be zero-extended, instead of sign-extended.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
---
 include/qemu/host-utils.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Richard Henderson Oct. 21, 2021, 8:02 p.m. UTC | #1 
On 9/10/21 4:26 AM, Luis Pires wrote:
> *plow (lower 64 bits of the dividend) is passed into divs128() as
> a signed 64-bit integer. When building an __int128_t from it, it
> must be zero-extended, instead of sign-extended.
> 
> Suggested-by: Richard Henderson<richard.henderson@linaro.org>
> Signed-off-by: Luis Pires<luis.pires@eldorado.org.br>
> ---
>   include/qemu/host-utils.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
diff mbox series

Patch

diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h
index 711b221704..753b9fb89f 100644
--- a/include/qemu/host-utils.h
+++ b/include/qemu/host-utils.h
@@ -70,7 +70,7 @@  static inline int divs128(int64_t *plow, int64_t *phigh, int64_t divisor)
     if (divisor == 0) {
         return 1;
     } else {
-        __int128_t dividend = ((__int128_t)*phigh << 64) | *plow;
+        __int128_t dividend = ((__int128_t)*phigh << 64) | (uint64_t)*plow;
         __int128_t result = dividend / divisor;
         *plow = result;
         *phigh = dividend % divisor;