[PATCH 2/2] lib/hash: avoid implicit conversion to 64 bit number

Andre Muezerie andremue at linux.microsoft.com
Thu Nov 28 02:53:57 CET 2024


MSVC issues the warnings below:

1) ../lib/hash/rte_thash_gf2_poly_math.c(128): warning C4334: '<<':
    result of 32-bit shift implicitly converted to 64 bits
    (was 64-bit shift intended?)

The code would be better off by using 64 bit numbers to begin with.
That eliminates the need for a conversion to 64 bits later.

2) ../lib/hash/rte_thash.c(568): warning C4334: '<<':
    result of 32-bit shift implicitly converted to 64 bits
    (was 64-bit shift intended?)

1ULL should be used as the result of the bit shift gets multiplied
by sizeof(uint32_t).

Signed-off-by: Andre Muezerie <andremue at linux.microsoft.com>
---
 lib/hash/rte_thash.c               | 2 +-
 lib/hash/rte_thash_gf2_poly_math.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
index fa78787143..f076311b57 100644
--- a/lib/hash/rte_thash.c
+++ b/lib/hash/rte_thash.c
@@ -565,7 +565,7 @@ rte_thash_add_helper(struct rte_thash_ctx *ctx, const char *name, uint32_t len,
 		offset;
 
 	ent = rte_zmalloc(NULL, sizeof(struct rte_thash_subtuple_helper) +
-		sizeof(uint32_t) * (1 << ctx->reta_sz_log),
+		sizeof(uint32_t) * (1ULL << ctx->reta_sz_log),
 		RTE_CACHE_LINE_SIZE);
 	if (ent == NULL)
 		return -ENOMEM;
diff --git a/lib/hash/rte_thash_gf2_poly_math.c b/lib/hash/rte_thash_gf2_poly_math.c
index 825da4382f..858884b4d4 100644
--- a/lib/hash/rte_thash_gf2_poly_math.c
+++ b/lib/hash/rte_thash_gf2_poly_math.c
@@ -119,16 +119,16 @@ static uint32_t
 gf2_mul(uint32_t a, uint32_t b, uint32_t r, int degree)
 {
 	uint64_t product = 0;
-	uint64_t r_poly = r|(1ULL << degree);
+	uint64_t r_poly = r | RTE_BIT64(degree);
 
 	for (; b; b &= (b - 1))
 		product ^= (uint64_t)a << (rte_bsf32(b));
 
 	for (int i = degree * 2 - 1; i >= degree; i--)
-		if (product & (1 << i))
+		if (product & RTE_BIT64(i))
 			product ^= r_poly << (i - degree);
 
-	return product;
+	return (uint32_t)product;
 }
 
 static uint32_t
-- 
2.47.0.vfs.0.3



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