Changeset 50541 in webkit for trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h

Timestamp:

Nov 4, 2009, 9:02:09 PM (16 years ago)

Author:

[email protected]

Message:

​https://bugs.webkit.org/show_bug.cgi?id=31151
Fix branchDouble behaviour on ARM THUMB2 JIT.

Patch by Gavin Barraclough <​[email protected]> on 2009-11-04
Reviewed by Oliver Hunt.

The ARMv7 JIT is currently using ARMv7Assembler::ConditionEQ to branch
for DoubleEqualOrUnordered, however this is incorrect – ConditionEQ won't
branch on unordered operands. Similarly, DoubleLessThanOrUnordered &
DoubleLessThanOrEqualOrUnordered use ARMv7Assembler::ConditionLO &
ARMv7Assembler::ConditionLS, whereas they should be using
ARMv7Assembler::ConditionLT & ARMv7Assembler::ConditionLE.

Fix these, and fill out the missing DoubleConditions.

• assembler/MacroAssemblerARMv7.h:

(JSC::MacroAssemblerARMv7::):
(JSC::MacroAssemblerARMv7::branchDouble):

File:

• trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h (modified) (2 diffs)

trunk/JavaScriptCore/assembler/MacroAssemblerARMv7.h

@@ -94 +94 @@
         NonZero = ARMv7Assembler::ConditionNE
     };
-
     enum DoubleCondition {
-        DoubleEqualOrUnordered = ARMv7Assembler::ConditionEQ,
+        // These conditions will only evaluate to true if the comparison is ordered - i.e. neither operand is NaN.
+        DoubleEqual = ARMv7Assembler::ConditionEQ,
+        DoubleNotEqual = ARMv7Assembler::ConditionVC, // Not the right flag! check for this & handle differently.
         DoubleGreaterThan = ARMv7Assembler::ConditionGT,
         DoubleGreaterThanOrEqual = ARMv7Assembler::ConditionGE,
-        DoubleLessThanOrUnordered = ARMv7Assembler::ConditionLO,
-        DoubleLessThanOrEqualOrUnordered = ARMv7Assembler::ConditionLS,
+        DoubleLessThan = ARMv7Assembler::ConditionLO,
+        DoubleLessThanOrEqual = ARMv7Assembler::ConditionLS,
+        // If either operand is NaN, these conditions always evaluate to true.
+        DoubleEqualOrUnordered = ARMv7Assembler::ConditionVS, // Not the right flag! check for this & handle differently.
+        DoubleNotEqualOrUnordered = ARMv7Assembler::ConditionNE,
+        DoubleGreaterThanOrUnordered = ARMv7Assembler::ConditionHI,
+        DoubleGreaterThanOrEqualOrUnordered = ARMv7Assembler::ConditionHS,
+        DoubleLessThanOrUnordered = ARMv7Assembler::ConditionLT,
+        DoubleLessThanOrEqualOrUnordered = ARMv7Assembler::ConditionLE,
     };
 
@@ -532 +540 @@
         m_assembler.vcmp_F64(left, right);
         m_assembler.vmrs_APSR_nzcv_FPSCR();
+
+        if (cond == DoubleNotEqual) {
+            // ConditionNE jumps if NotEqual *or* unordered - force the unordered cases not to jump.
+            Jump unordered = makeBranch(ARMv7Assembler::ConditionVS);
+            Jump result = makeBranch(ARMv7Assembler::ConditionNE);
+            unordered.link(this);
+            return result;
+        }
+        if (cond == DoubleEqualOrUnordered) {
+            Jump unordered = makeBranch(ARMv7Assembler::ConditionVS);
+            Jump notEqual = makeBranch(ARMv7Assembler::ConditionNE);
+            unordered.link(this);
+            // We get here if either unordered, or equal.
+            Jump result = makeJump();
+            notEqual.link(this);
+            return result;
+        }
         return makeBranch(cond);
     }