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authorPeter Maydell <peter.maydell@linaro.org>2021-08-13 17:11:48 +0100
committerPeter Maydell <peter.maydell@linaro.org>2021-08-25 10:48:48 +0100
commit3f4f1880c245453b75d4c09049845b19de9964bf (patch)
treeddbd59a43791d80d5e929ca9e40f4185c042a7e7
parentfdcf2269c4e0e4f5ca3a389290a71d7aa98bd5c7 (diff)
downloadfocaccia-qemu-3f4f1880c245453b75d4c09049845b19de9964bf.tar.gz
focaccia-qemu-3f4f1880c245453b75d4c09049845b19de9964bf.zip
target/arm: Fix calculation of LTP mask when LR is 0
In mve_element_mask(), we calculate a mask for tail predication which
should have a number of 1 bits based on the value of LR.  However,
our MAKE_64BIT_MASK() macro has undefined behaviour when passed a
zero length.  Special case this to give the all-zeroes mask we
require.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
-rw-r--r--target/arm/mve_helper.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/target/arm/mve_helper.c b/target/arm/mve_helper.c
index 1a4b2ef807..bc67b86e70 100644
--- a/target/arm/mve_helper.c
+++ b/target/arm/mve_helper.c
@@ -64,7 +64,8 @@ static uint16_t mve_element_mask(CPUARMState *env)
          */
         int masklen = env->regs[14] << env->v7m.ltpsize;
         assert(masklen <= 16);
-        mask &= MAKE_64BIT_MASK(0, masklen);
+        uint16_t ltpmask = masklen ? MAKE_64BIT_MASK(0, masklen) : 0;
+        mask &= ltpmask;
     }
 
     if ((env->condexec_bits & 0xf) == 0) {