[Webkit-unassigned] [Bug 159419] New: [ARM] REGRESSION(r197655): ASSERTION FAILED: (cond == Zero) || (cond == NonZero)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=159419

            Bug ID: 159419
           Summary: [ARM] REGRESSION(r197655): ASSERTION FAILED: (cond ==
                    Zero) || (cond == NonZero)
    Classification: Unclassified
           Product: WebKit
           Version: Other
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Critical
          Priority: P1
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: ossy at webkit.org
                CC: benjamin at webkit.org, fpizlo at apple.com
            Blocks: 155066

https://trac.webkit.org/changeset/197655 modified the code in compileArithMul()
to check negative zero:
-            speculationCheck(NegativeZero, JSValueRegs(), 0, m_jit.branch32(MacroAssembler::LessThan, reg1, TrustedImm32(0)));
-            speculationCheck(NegativeZero, JSValueRegs(), 0, m_jit.branch32(MacroAssembler::LessThan, reg2, TrustedImm32(0)));
+            speculationCheck(NegativeZero, JSValueRegs(), 0, m_jit.branchTest32(MacroAssembler::Signed, reg1));
+            speculationCheck(NegativeZero, JSValueRegs(), 0, m_jit.branchTest32(MacroAssembler::Signed, reg2));

Using branchTest32 with signed conditional flag is incorrect, because the underlying 
tst ARM assembly instruction doesn't affect the V (signed/overflow) flag at all.

The MacroAssemblerARM.h asserts in this case properly.

ASSERTION FAILED: (cond == Zero) || (cond == NonZero)
../../Source/JavaScriptCore/assembler/MacroAssemblerARM.h(714) : JSC::AbstractMacroAssembler<JSC::ARMAssembler, JSC::MacroAssemblerARM>::Jump JSC::MacroAssemblerARM::branchTest32(JSC::MacroAssemblerARM::ResultCondition, JSC::AbstractMacroAssembler<JSC::ARMAssembler, JSC::MacroAssemblerARM>::RegisterID, JSC::AbstractMacroAssembler<JSC::ARMAssembler, JSC::MacroAssemblerARM>::TrustedImm32)
1   0x41af4060 WTFCrash
2   0x40fa0a20 JSC::MacroAssemblerARM::branchTest32(JSC::MacroAssemblerARM::ResultCondition, JSC::ARMRegisters::RegisterID, JSC::AbstractMacroAssembler<JSC::ARMAssembler, JSC::MacroAssemblerARM>::TrustedImm32)
3   0x413ab1e0 JSC::DFG::SpeculativeJIT::compileArithMul(JSC::DFG::Node*)
4   0x41410fec JSC::DFG::SpeculativeJIT::compile(JSC::DFG::Node*)
5   0x4139f5ec JSC::DFG::SpeculativeJIT::compileCurrentBlock()
6   0x4139fcec JSC::DFG::SpeculativeJIT::compile()
7   0x4127220c JSC::DFG::JITCompiler::compileBody()
8   0x41273e04 JSC::DFG::JITCompiler::compileFunction()
9   0x4134ed18 JSC::DFG::Plan::compileInThreadImpl(JSC::DFG::LongLivedState&)
10  0x4134e078 JSC::DFG::Plan::compileInThread(JSC::DFG::LongLivedState&, JSC::DFG::ThreadData*)
11  0x411f2e88
12  0x411f2fec JSC::DFG::compile(JSC::VM&, JSC::CodeBlock*, JSC::CodeBlock*, JSC::DFG::CompilationMode, unsigned int, JSC::Operands<JSC::JSValue, JSC::OperandValueTraits<JSC::JSValue> > const&, WTF::PassRefPtr<JSC::DeferredCompilationCallback>)
13  0x41600004
Illegal instruction
ERROR: Unexpected exit code: 132

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