From a7ab4e552766bf127776c198d1b844fea72b86d0 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Tue, 17 Jul 2012 16:36:50 -0700
Subject: [PATCH] Bug 771378 (part 1) - Remove use of MUST_FLOW_THROUGH from
 BytecodeEmitter.cpp.  r=jwalden.

--HG--
extra : rebase_source : c45808569daa61d10bd57fdc5b969e4880cc3ada
---
 js/src/frontend/BytecodeEmitter.cpp | 51 +++++++++--------------------
 1 file changed, 16 insertions(+), 35 deletions(-)

diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index 12c14a5ed5f..1b096e58368 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -2204,11 +2204,9 @@ MOZ_NEVER_INLINE static bool
 EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
 {
     JSOp switchOp;
-    bool ok, hasDefault;
+    bool hasDefault;
     ptrdiff_t top, off, defaultOffset;
     ParseNode *pn2, *pn3, *pn4;
-    uint32_t caseCount, tableLength;
-    ParseNode **table;
     int32_t i, low, high;
     int noteIndex;
     size_t switchSize, tableSize;
@@ -2217,7 +2215,6 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
 
     /* Try for most optimal, fall back if not dense ints, and per ECMAv2. */
     switchOp = JSOP_TABLESWITCH;
-    ok = true;
     hasDefault = false;
     defaultOffset = -1;
 
@@ -2269,9 +2266,9 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
     }
 #endif
 
-    caseCount = pn2->pn_count;
-    tableLength = 0;
-    table = NULL;
+    uint32_t caseCount = pn2->pn_count;
+    uint32_t tableLength = 0;
+    js::ScopedFreePtr<ParseNode*> table(NULL);
 
     if (caseCount == 0 ||
         (caseCount == 1 &&
@@ -2280,6 +2277,7 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
         low = 0;
         high = -1;
     } else {
+        bool ok = true;
 #define INTMAP_LENGTH   256
         jsbitmap intmap_space[INTMAP_LENGTH];
         jsbitmap *intmap = NULL;
@@ -2510,8 +2508,7 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
 
             /*
              * Use malloc to avoid arena bloat for programs with many switches.
-             * We free table if non-null at label out, so all control flow must
-             * exit this function through goto out or goto bad.
+             * ScopedFreePtr takes care of freeing it on exit.
              */
             if (tableLength != 0) {
                 tableSize = (size_t)tableLength * sizeof *table;
@@ -2535,13 +2532,6 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
             SET_UINT16(pc, caseCount);
             pc += UINT16_LEN;
         }
-
-        /*
-         * After this point, all control flow involving JSOP_TABLESWITCH
-         * must set ok and goto out to exit this function.  To keep things
-         * simple, all switchOp cases exit that way.
-         */
-        MUST_FLOW_THROUGH("out");
     }
 
     /* Emit code for each case's statements, copying pn_offset up to pn3. */
@@ -2549,9 +2539,8 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
         if (switchOp == JSOP_CONDSWITCH && !pn3->isKind(PNK_DEFAULT))
             SetJumpOffsetAt(bce, pn3->pn_offset);
         pn4 = pn3->pn_right;
-        ok = EmitTree(cx, bce, pn4);
-        if (!ok)
-            goto out;
+        if (!EmitTree(cx, bce, pn4))
+            return false;
         pn3->pn_offset = pn4->pn_offset;
         if (pn3->isKind(PNK_DEFAULT))
             off = pn3->pn_offset - top;
@@ -2578,9 +2567,8 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
 
     /* Set the SRC_SWITCH note's offset operand to tell end of switch. */
     off = bce->offset() - top;
-    ok = SetSrcNoteOffset(cx, bce, (unsigned)noteIndex, 0, off);
-    if (!ok)
-        goto out;
+    if (!SetSrcNoteOffset(cx, bce, (unsigned)noteIndex, 0, off))
+        return false;
 
     if (switchOp == JSOP_TABLESWITCH) {
         /* Skip over the already-initialized switch bounds. */
@@ -2601,7 +2589,7 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
             if (pn3->isKind(PNK_DEFAULT))
                 continue;
             if (!bce->constList.append(*pn3->pn_pval))
-                goto bad;
+                return false;
             SET_UINT32_INDEX(pc, bce->constList.length() - 1);
             pc += UINT32_INDEX_LEN;
 
@@ -2611,22 +2599,15 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
         }
     }
 
-out:
-    if (table)
-        cx->free_(table);
-    if (ok) {
-        ok = PopStatementBCE(cx, bce);
+    if (!PopStatementBCE(cx, bce))
+        return false;
 
 #if JS_HAS_BLOCK_SCOPE
-        if (ok && pn->pn_right->isKind(PNK_LEXICALSCOPE))
-            EMIT_UINT16_IMM_OP(JSOP_LEAVEBLOCK, blockObjCount);
+    if (pn->pn_right->isKind(PNK_LEXICALSCOPE))
+        EMIT_UINT16_IMM_OP(JSOP_LEAVEBLOCK, blockObjCount);
 #endif
-    }
-    return ok;
 
-bad:
-    ok = false;
-    goto out;
+    return true;
 }
 
 bool