From: Paul Floyd <pjfloyd@wanadoo.fr>
Date: Thu, 28 Mar 2024 08:06:23 +0000 (+0100)
Subject: coverity: dead code and overflows
X-Git-Tag: VALGRIND_3_23_0~88
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ba728d01c09438a044a57888e89654789a12d8c9;p=thirdparty%2Fvalgrind.git

coverity: dead code and overflows

Overflows deliberate. Dead code probably not.
---

diff --git a/VEX/priv/guest_amd64_helpers.c b/VEX/priv/guest_amd64_helpers.c
index adb5c7287..da1cabc3c 100644
--- a/VEX/priv/guest_amd64_helpers.c
+++ b/VEX/priv/guest_amd64_helpers.c
@@ -3662,7 +3662,6 @@ ULong amd64g_calculate_RCR ( ULong arg,
          }
          break;
       case 4:
-         while (tempCOUNT >= 33) tempCOUNT -= 33;
          cf        = (rflags_in >> AMD64G_CC_SHIFT_C) & 1;
          of        = ((arg >> 31) ^ cf) & 1;
          while (tempCOUNT > 0) {
@@ -3730,7 +3729,6 @@ ULong amd64g_calculate_RCL ( ULong arg,
          of = ((arg >> 63) ^ cf) & 1;
          break;
       case 4:
-         while (tempCOUNT >= 33) tempCOUNT -= 33;
          cf = (rflags_in >> AMD64G_CC_SHIFT_C) & 1;
          while (tempCOUNT > 0) {
             tempcf = (arg >> 31) & 1;
diff --git a/VEX/priv/guest_arm64_toIR.c b/VEX/priv/guest_arm64_toIR.c
index 8a8743866..3b33c48c3 100644
--- a/VEX/priv/guest_arm64_toIR.c
+++ b/VEX/priv/guest_arm64_toIR.c
@@ -8047,8 +8047,13 @@ static Bool AdvSIMDExpandImm ( /*OUT*/ULong* res,
       case 1:
          testimm8 = True; imm64 = Replicate32x2(imm8 << 8UL); break;
       case 2:
+         // Coverity is right but we want the overflow, Replicate32x2 expects
+         // (and asserts) that the top 32bits be zero so if we get rid of the
+         // overflow we would need to add a mask. So just let it overflow.
+         // coverity[OVERFLOW_BEFORE_WIDEN:FALSE]
          testimm8 = True; imm64 = Replicate32x2(imm8 << 16UL); break;
       case 3:
+         // coverity[OVERFLOW_BEFORE_WIDEN:FALSE]
          testimm8 = True; imm64 = Replicate32x2(imm8 << 24UL); break;
       case 4:
           testimm8 = False; imm64 = Replicate16x4(imm8); break;