Improved comments on the VDBE branch coverage testing logic. Fix the

VDBE branch coverage measurement on the OP_MustBeInt opcode.

FossilOrigin-Name: 8681750e855a020ee374cb9f973f701a72068e33f97d0101a4fab3a228e5ebda

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\sdefect\sin\sthe\sVDBE\sbranch\scoverage\stesting\slogic.
+C Improved\scomments\son\sthe\sVDBE\sbranch\scoverage\stesting\slogic.\s\sFix\sthe\nVDBE\sbranch\scoverage\smeasurement\son\sthe\sOP_MustBeInt\sopcode.
-D 2019-04-01T13:06:19.535
+D 2019-04-01T14:01:21.321
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -588,7 +588,7 @@ F src/upsert.c 0dd81b40206841814d46942a7337786932475f085716042d0cb2fc7791bf8ca4
 F src/utf.c 810fbfebe12359f10bc2a011520a6e10879ab2a163bcb26c74768eab82ea62a5
 F src/util.c 82a2e3f691a3b654be872e305dab1f455e565dedf5e6a90c818c1ab307c00432
 F src/vacuum.c 532553ee1d47f69c1198858107b1f3af3d16af25f2ab4ce3b1263d9e333f26e2
-F src/vdbe.c 1528ce3ba17a3e6fea4e6826a1fe3a0720649eecf9ec95b50b49c05a98039214
+F src/vdbe.c eeaf0af94b48379b01a25566013138a68e286c82a2da68b2ab30974442518470
 F src/vdbe.h 712bca562eaed1c25506b9faf9680bdc75fc42e2f4a1cd518d883fa79c7a4237
 F src/vdbeInt.h a76d5eed62c76bcd8de7afd3147fac1bc40c5a870582664bcd7d071ef437c37f
 F src/vdbeapi.c 7a052df80d7e2e55382076174633e888f21fe200feb5d49b1b441b4c38ab851a
@@ -1814,7 +1814,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 6cf8b18ec20f11c25ff7396f29c742404d3a88d5e97a5fd53ccfaff51dec3f33
+P 1fcf3307d37f0e8e0c8c54491c609b73c7add6eaa38409a41c7cd6614a877a19
-R b92610a214fa68c9d99cf58b794058b4
+R 548d264b85d1f84e31c647fc92a651ab
 U drh
-Z 48bc3a72c5a2f4b3ff012adefbb09d94
+Z 3917bade205e6ba6a19fe2a0919e61ee

manifest.uuid

@@ -1 +1 @@
-1fcf3307d37f0e8e0c8c54491c609b73c7add6eaa38409a41c7cd6614a877a19
+8681750e855a020ee374cb9f973f701a72068e33f97d0101a4fab3a228e5ebda

src/vdbe.c

@@ -122,12 +122,20 @@ int sqlite3_found_count = 0;
 ** feature is used for test suite validation only and does not appear an
 ** production builds.
 **
-** M is an integer between 2 and 4.  2 indicates a ordinary two-way
+** M is the type of branch.  I is the direction taken for this instance of
-** branch (I=0 means fall through and I=1 means taken).  3 indicates
+** the branch.
-** a 3-way branch where the third way is when one of the operands is
+**
-** NULL.  4 indicates the OP_Jump instruction which has three destinations
+**   M: 2 - two-way branch (I=0: fall-thru   1: jump                )
-** depending on whether the first operand is less than, equal to, or greater
+**      3 - two-way + NULL (I=0: fall-thru   1: jump      2: NULL   )
-** than the second. 
+**      4 - OP_Jump        (I=0: jump p1     1: jump p2   2: jump p3)
+**
+** In other words, if M is 2, then I is either 0 (for fall-through) or
+** 1 (for when the branch is taken).  If M is 3, the I is 0 for an
+** ordinary fall-through, I is 1 if the branch was taken, and I is 2 
+** if the result of comparison is NULL.  For M=3, I=2 the jump may or
+** may not be taken, depending on the SQLITE_JUMPIFNULL flags in p5.
+** When M is 4, that means that an OP_Jump is being run.  I is 0, 1, or 2
+** depending on if the operands are less than, equal, or greater than.
 **
 ** iSrcLine is the source code line (from the __LINE__ macro) that
 ** generated the VDBE instruction combined with flag bits.  The source
@@ -138,9 +146,9 @@ int sqlite3_found_count = 0;
 ** alternate branch are never taken.  If a branch is never taken then
 ** flags should be 0x06 since only the fall-through approach is allowed.
 **
-** Bit 0x04 of the flags indicates an OP_Jump opcode that is only
+** Bit 0x08 of the flags indicates an OP_Jump opcode that is only
 ** interested in equal or not-equal.  In other words, I==0 and I==2
-** should be treated the same.
+** should be treated as equivalent
 **
 ** Since only a line number is retained, not the filename, this macro
 ** only works for amalgamation builds.  But that is ok, since these macros
@@ -164,6 +172,18 @@ int sqlite3_found_count = 0;
     mNever = iSrcLine >> 24;
     assert( (I & mNever)==0 );
     if( sqlite3GlobalConfig.xVdbeBranch==0 ) return;  /*NO_TEST*/
+    /* Invoke the branch coverage callback with three arguments:
+    **    iSrcLine - the line number of the VdbeCoverage() macro, with
+    **               flags removed.
+    **    I        - Mask of bits 0x07 indicating which cases are are
+    **               fulfilled by this instance of the jump.  0x01 means
+    **               fall-thru, 0x02 means taken, 0x04 means NULL.  Any
+    **               impossible cases (ex: if the comparison is never NULL)
+    **               are filled in automatically so that the coverage
+    **               measurement logic does not flag those impossible cases
+    **               as missed coverage.
+    **    M        - Type of jump.  Same as M argument above
+    */
     I |= mNever;
     if( M==2 ) I |= 0x04;
     if( M==4 ){
@@ -1734,8 +1754,8 @@ case OP_MustBeInt: {            /* jump, in1 */
   pIn1 = &aMem[pOp->p1];
   if( (pIn1->flags & MEM_Int)==0 ){
     applyAffinity(pIn1, SQLITE_AFF_NUMERIC, encoding);
-    VdbeBranchTaken((pIn1->flags&MEM_Int)==0, 2);
     if( (pIn1->flags & MEM_Int)==0 ){
+      VdbeBranchTaken(1, 2);
       if( pOp->p2==0 ){
         rc = SQLITE_MISMATCH;
         goto abort_due_to_error;
@@ -1744,6 +1764,7 @@ case OP_MustBeInt: {            /* jump, in1 */
       }
     }
   }
+  VdbeBranchTaken(0, 2);
   MemSetTypeFlag(pIn1, MEM_Int);
   break;
 }