From c1757a6deab0ca0bfd42c38612d92b2f26c41dbe Mon Sep 17 00:00:00 2001 From: buzbee Date: Mon, 11 Feb 2013 16:52:31 -0800 Subject: Fix JIT bug related to immediate doubles Change 256211 (JIT: Performance Fix for const doubles) introduced a defect that can cause the JIT to use the wrong floating point double constant in traces in which the following conditions hold: o Two (or more) different 64-bit floating point constants are used. o The physical register holding the first constant is still live at the time the second constant is used. o The low 32 bits of the two constants are identical. In this situation, the load/copy optimization pass will incorrectly determine that the two constants are the same, delete the load of the second constant and re-use the first constant value. Note: this problem only occurs with 64-bit floating point literals. 64-bit long literals are unaffected. This CL works around the problem, and a subsequent CL will rework disambiguation of 64-bit immediates in a somewhat cleaner fashion. Change-Id: I33baf78402bab58d9b0ca46189f26491c2b2a751 --- vm/compiler/codegen/arm/Thumb2/Factory.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'vm/compiler/codegen/arm') diff --git a/vm/compiler/codegen/arm/Thumb2/Factory.cpp b/vm/compiler/codegen/arm/Thumb2/Factory.cpp index c3c37128c..b9265e823 100644 --- a/vm/compiler/codegen/arm/Thumb2/Factory.cpp +++ b/vm/compiler/codegen/arm/Thumb2/Factory.cpp @@ -727,7 +727,8 @@ static ArmLIR *loadConstantValueWide(CompilationUnit *cUnit, int rDestLo, loadPcRel->operands[1] = r15pc; setupResourceMasks(loadPcRel); setMemRefType(loadPcRel, true, kLiteral); - loadPcRel->aliasInfo = dataTarget->operands[0]; + // TODO: rework literal load disambiguation to more cleanly handle 64-bit loads + loadPcRel->aliasInfo = (uintptr_t)dataTarget; dvmCompilerAppendLIR(cUnit, (LIR *) loadPcRel); res = loadPcRel; } -- cgit v1.2.3