Simplify executor's handling of CaseTestExpr & CoerceToDomainValue.

Instead of deciding at runtime whether to read from casetest.value
or caseValue_datum, split EEOP_CASE_TESTVAL into two opcodes and
make the decision during expression compilation.  Similarly for
EEOP_DOMAIN_TESTVAL.  This actually results in net less code,
mainly because llvmjit_expr.c's code for handling these opcodes
gets shorter.  The performance gain is doubtless negligible, but
this seems worth changing anyway on grounds of simplicity and
understandability.

Author: Andreas Karlsson <[email protected]>
Co-authored-by: Xing Guo <[email protected]>
Reviewed-by: Tom Lane <[email protected]>
Discussion: https://postgr.es/m/CACpMh+AiBYAWn+D1aU7Rsy-V1tox06Cbc0H3qA7rwL5zdJ=anQ@mail.gmail.com

diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 8f28da4bf94562af90bb0ffda5624e76dae487a2..03566c4d18166f7379eef32a593fd2bee255c8a9 100644 (file)
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -1901,13 +1901,17 @@ ExecInitExprRec(Expr *node, ExprState *state,
                 * actually within a CaseExpr, ArrayCoerceExpr, etc structure.
                 * That can happen because some parts of the system abuse
                 * CaseTestExpr to cause a read of a value externally supplied
-                * in econtext->caseValue_datum.  We'll take care of that
-                * scenario at runtime.
+                * in econtext->caseValue_datum.  We'll take care of that by
+                * generating a specialized operation.
                 */
-               scratch.opcode = EEOP_CASE_TESTVAL;
-               scratch.d.casetest.value = state->innermost_caseval;
-               scratch.d.casetest.isnull = state->innermost_casenull;
-
+               if (state->innermost_caseval == NULL)
+                   scratch.opcode = EEOP_CASE_TESTVAL_EXT;
+               else
+               {
+                   scratch.opcode = EEOP_CASE_TESTVAL;
+                   scratch.d.casetest.value = state->innermost_caseval;
+                   scratch.d.casetest.isnull = state->innermost_casenull;
+               }
                ExprEvalPushStep(state, &scratch);
                break;
            }
@@ -2594,14 +2598,18 @@ ExecInitExprRec(Expr *node, ExprState *state,
                 * that innermost_domainval could be NULL, if we're compiling
                 * a standalone domain check rather than one embedded in a
                 * larger expression.  In that case we must read from
-                * econtext->domainValue_datum.  We'll take care of that
-                * scenario at runtime.
+                * econtext->domainValue_datum.  We'll take care of that by
+                * generating a specialized operation.
                 */
-               scratch.opcode = EEOP_DOMAIN_TESTVAL;
-               /* we share instruction union variant with case testval */
-               scratch.d.casetest.value = state->innermost_domainval;
-               scratch.d.casetest.isnull = state->innermost_domainnull;
-
+               if (state->innermost_domainval == NULL)
+                   scratch.opcode = EEOP_DOMAIN_TESTVAL_EXT;
+               else
+               {
+                   scratch.opcode = EEOP_DOMAIN_TESTVAL;
+                   /* we share instruction union variant with case testval */
+                   scratch.d.casetest.value = state->innermost_domainval;
+                   scratch.d.casetest.isnull = state->innermost_domainnull;
+               }
                ExprEvalPushStep(state, &scratch);
                break;
            }

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 1127e6f11eb854ceba0cc356015598f443142309..09f6a5f14c1d22f4cd33dec55cc1eabf7b4e5a9b 100644 (file)
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -365,8 +365,7 @@ ExecReadyInterpretedExpr(ExprState *state)
            return;
        }
        else if (step0 == EEOP_CASE_TESTVAL &&
-                step1 == EEOP_FUNCEXPR_STRICT &&
-                state->steps[0].d.casetest.value)
+                step1 == EEOP_FUNCEXPR_STRICT)
        {
            state->evalfunc_private = ExecJustApplyFuncToCase;
            return;
@@ -524,6 +523,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
        &&CASE_EEOP_PARAM_CALLBACK,
        &&CASE_EEOP_PARAM_SET,
        &&CASE_EEOP_CASE_TESTVAL,
+       &&CASE_EEOP_CASE_TESTVAL_EXT,
        &&CASE_EEOP_MAKE_READONLY,
        &&CASE_EEOP_IOCOERCE,
        &&CASE_EEOP_IOCOERCE_SAFE,
@@ -548,6 +548,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
        &&CASE_EEOP_SBSREF_ASSIGN,
        &&CASE_EEOP_SBSREF_FETCH,
        &&CASE_EEOP_DOMAIN_TESTVAL,
+       &&CASE_EEOP_DOMAIN_TESTVAL_EXT,
        &&CASE_EEOP_DOMAIN_NOTNULL,
        &&CASE_EEOP_DOMAIN_CHECK,
        &&CASE_EEOP_HASHDATUM_SET_INITVAL,
@@ -1273,44 +1274,16 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 
        EEO_CASE(EEOP_CASE_TESTVAL)
        {
-           /*
-            * Normally upper parts of the expression tree have setup the
-            * values to be returned here, but some parts of the system
-            * currently misuse {caseValue,domainValue}_{datum,isNull} to set
-            * run-time data.  So if no values have been set-up, use
-            * ExprContext's.  This isn't pretty, but also not *that* ugly,
-            * and this is unlikely to be performance sensitive enough to
-            * worry about an extra branch.
-            */
-           if (op->d.casetest.value)
-           {
-               *op->resvalue = *op->d.casetest.value;
-               *op->resnull = *op->d.casetest.isnull;
-           }
-           else
-           {
-               *op->resvalue = econtext->caseValue_datum;
-               *op->resnull = econtext->caseValue_isNull;
-           }
+           *op->resvalue = *op->d.casetest.value;
+           *op->resnull = *op->d.casetest.isnull;
 
            EEO_NEXT();
        }
 
-       EEO_CASE(EEOP_DOMAIN_TESTVAL)
+       EEO_CASE(EEOP_CASE_TESTVAL_EXT)
        {
-           /*
-            * See EEOP_CASE_TESTVAL comment.
-            */
-           if (op->d.casetest.value)
-           {
-               *op->resvalue = *op->d.casetest.value;
-               *op->resnull = *op->d.casetest.isnull;
-           }
-           else
-           {
-               *op->resvalue = econtext->domainValue_datum;
-               *op->resnull = econtext->domainValue_isNull;
-           }
+           *op->resvalue = econtext->caseValue_datum;
+           *op->resnull = econtext->caseValue_isNull;
 
            EEO_NEXT();
        }
@@ -1726,6 +1699,22 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
            EEO_NEXT();
        }
 
+       EEO_CASE(EEOP_DOMAIN_TESTVAL)
+       {
+           *op->resvalue = *op->d.casetest.value;
+           *op->resnull = *op->d.casetest.isnull;
+
+           EEO_NEXT();
+       }
+
+       EEO_CASE(EEOP_DOMAIN_TESTVAL_EXT)
+       {
+           *op->resvalue = econtext->domainValue_datum;
+           *op->resnull = econtext->domainValue_isNull;
+
+           EEO_NEXT();
+       }
+
        EEO_CASE(EEOP_DOMAIN_NOTNULL)
        {
            /* too complex for an inline implementation */

diff --git a/src/backend/jit/llvm/llvmjit_expr.c b/src/backend/jit/llvm/llvmjit_expr.c
index c1cf34f10346f86db5285fcc10ac56ea13b77707..f0f5c3bd49f9710c4b0e1639b0e641c3aace43eb 100644 (file)
--- a/src/backend/jit/llvm/llvmjit_expr.c
+++ b/src/backend/jit/llvm/llvmjit_expr.c
@@ -1265,41 +1265,30 @@ llvm_compile_expr(ExprState *state)
 
            case EEOP_CASE_TESTVAL:
                {
-                   LLVMBasicBlockRef b_avail,
-                               b_notavail;
                    LLVMValueRef v_casevaluep,
                                v_casevalue;
                    LLVMValueRef v_casenullp,
                                v_casenull;
-                   LLVMValueRef v_casevaluenull;
-
-                   b_avail = l_bb_before_v(opblocks[opno + 1],
-                                           "op.%d.avail", opno);
-                   b_notavail = l_bb_before_v(opblocks[opno + 1],
-                                              "op.%d.notavail", opno);
 
                    v_casevaluep = l_ptr_const(op->d.casetest.value,
                                               l_ptr(TypeSizeT));
                    v_casenullp = l_ptr_const(op->d.casetest.isnull,
                                              l_ptr(TypeStorageBool));
 
-                   v_casevaluenull =
-                       LLVMBuildICmp(b, LLVMIntEQ,
-                                     LLVMBuildPtrToInt(b, v_casevaluep,
-                                                       TypeSizeT, ""),
-                                     l_sizet_const(0), "");
-                   LLVMBuildCondBr(b, v_casevaluenull, b_notavail, b_avail);
-
-                   /* if casetest != NULL */
-                   LLVMPositionBuilderAtEnd(b, b_avail);
                    v_casevalue = l_load(b, TypeSizeT, v_casevaluep, "");
                    v_casenull = l_load(b, TypeStorageBool, v_casenullp, "");
                    LLVMBuildStore(b, v_casevalue, v_resvaluep);
                    LLVMBuildStore(b, v_casenull, v_resnullp);
+
                    LLVMBuildBr(b, opblocks[opno + 1]);
+                   break;
+               }
+
+           case EEOP_CASE_TESTVAL_EXT:
+               {
+                   LLVMValueRef v_casevalue;
+                   LLVMValueRef v_casenull;
 
-                   /* if casetest == NULL */
-                   LLVMPositionBuilderAtEnd(b, b_notavail);
                    v_casevalue =
                        l_load_struct_gep(b,
                                          StructExprContext,
@@ -1958,43 +1947,30 @@ llvm_compile_expr(ExprState *state)
 
            case EEOP_DOMAIN_TESTVAL:
                {
-                   LLVMBasicBlockRef b_avail,
-                               b_notavail;
                    LLVMValueRef v_casevaluep,
                                v_casevalue;
                    LLVMValueRef v_casenullp,
                                v_casenull;
-                   LLVMValueRef v_casevaluenull;
-
-                   b_avail = l_bb_before_v(opblocks[opno + 1],
-                                           "op.%d.avail", opno);
-                   b_notavail = l_bb_before_v(opblocks[opno + 1],
-                                              "op.%d.notavail", opno);
 
                    v_casevaluep = l_ptr_const(op->d.casetest.value,
                                               l_ptr(TypeSizeT));
                    v_casenullp = l_ptr_const(op->d.casetest.isnull,
                                              l_ptr(TypeStorageBool));
 
-                   v_casevaluenull =
-                       LLVMBuildICmp(b, LLVMIntEQ,
-                                     LLVMBuildPtrToInt(b, v_casevaluep,
-                                                       TypeSizeT, ""),
-                                     l_sizet_const(0), "");
-                   LLVMBuildCondBr(b,
-                                   v_casevaluenull,
-                                   b_notavail, b_avail);
-
-                   /* if casetest != NULL */
-                   LLVMPositionBuilderAtEnd(b, b_avail);
                    v_casevalue = l_load(b, TypeSizeT, v_casevaluep, "");
                    v_casenull = l_load(b, TypeStorageBool, v_casenullp, "");
                    LLVMBuildStore(b, v_casevalue, v_resvaluep);
                    LLVMBuildStore(b, v_casenull, v_resnullp);
+
                    LLVMBuildBr(b, opblocks[opno + 1]);
+                   break;
+               }
+
+           case EEOP_DOMAIN_TESTVAL_EXT:
+               {
+                   LLVMValueRef v_casevalue;
+                   LLVMValueRef v_casenull;
 
-                   /* if casetest == NULL */
-                   LLVMPositionBuilderAtEnd(b, b_notavail);
                    v_casevalue =
                        l_load_struct_gep(b,
                                          StructExprContext,

diff --git a/src/include/executor/execExpr.h b/src/include/executor/execExpr.h
index 5371e344ecd91a6fc47cbe0649848dae3ded65fb..51bd35dcb078fbb10546a13ddd7b3117fcb8e02a 100644 (file)
--- a/src/include/executor/execExpr.h
+++ b/src/include/executor/execExpr.h
@@ -173,6 +173,7 @@ typedef enum ExprEvalOp
 
    /* return CaseTestExpr value */
    EEOP_CASE_TESTVAL,
+   EEOP_CASE_TESTVAL_EXT,
 
    /* apply MakeExpandedObjectReadOnly() to target value */
    EEOP_MAKE_READONLY,
@@ -237,6 +238,7 @@ typedef enum ExprEvalOp
 
    /* evaluate value for CoerceToDomainValue */
    EEOP_DOMAIN_TESTVAL,
+   EEOP_DOMAIN_TESTVAL_EXT,
 
    /* evaluate a domain's NOT NULL constraint */
    EEOP_DOMAIN_NOTNULL,