Status: New
Owner: ----
New issue 1019 by alexandre.rames: Missing vmrs after vcmp instructions on
ARM in LCodeGen::DoBranch
http://code.google.com/p/v8/issues/detail?id=1019
On ARM:
There are 2 vmrs(pc) instructions are missing in LCodeGen::DoBranch after
vcmp instructions.
Because of this the vfp status flags are not retrieved and the following
branches evaluate a wrong condition.
Bug discovered after implementing LCodeGen::DoStoreNamedField, which was
provoking many bailouts.
JS code showing the bug: (with --crankshaft --always_opt)
function test(a) {
print(a ? 1 : 0);
}
for(var i = -5; i < 5; i++) {
test(i + 0.1);
}
Index: src/arm/lithium-codegen-arm.cc
=======================
--- src/arm/lithium-codegen-arm.cc (revision 6149)
+++ src/arm/lithium-codegen-arm.cc (working copy)
@@ -1031,6 +1031,7 @@
} else if (r.IsDouble()) {
DoubleRegister reg = ToDoubleRegister(instr->input());
__ vcmp(reg, 0.0);
+ __ vmrs(pc); // Move vector status bits to normal status bits.
EmitBranch(true_block, false_block, ne);
} else {
ASSERT(r.IsTagged());
@@ -1069,6 +1070,7 @@
__ sub(ip, reg, Operand(kHeapObjectTag));
__ vldr(dbl_scratch, ip, HeapNumber::kValueOffset);
__ vcmp(dbl_scratch, 0.0);
+ __ vmrs(pc); // Move vector status bits to normal status bits.
__ b(eq, false_label);
__ b(true_label);
--
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