Add a 2 byte safety margin in offset computations.
ARMConstantIslandPass still has bugs where jump table compression can
cause constant pool entries to go out of range.
Add a safety margin of 2 bytes when placing constant islands, but use
the real max displacement for verification.
<rdar://problem/11156595>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153789 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMConstantIslandPass.cpp b/lib/Target/ARM/ARMConstantIslandPass.cpp
index f5221f0..fc35c7c 100644
--- a/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -209,8 +209,9 @@
}
/// getMaxDisp - Returns the maximum displacement supported by MI.
/// Correct for unknown alignment.
+ /// Conservatively subtract 2 bytes to handle weird alignment effects.
unsigned getMaxDisp() const {
- return KnownAlignment ? MaxDisp : MaxDisp - 2;
+ return (KnownAlignment ? MaxDisp : MaxDisp - 2) - 2;
}
};
@@ -350,7 +351,9 @@
for (unsigned i = 0, e = CPUsers.size(); i != e; ++i) {
CPUser &U = CPUsers[i];
unsigned UserOffset = getUserOffset(U);
- if (isCPEntryInRange(U.MI, UserOffset, U.CPEMI, U.getMaxDisp(), U.NegOk,
+ // Verify offset using the real max displacement without the safety
+ // adjustment.
+ if (isCPEntryInRange(U.MI, UserOffset, U.CPEMI, U.getMaxDisp()+2, U.NegOk,
/* DoDump = */ true)) {
DEBUG(dbgs() << "OK\n");
continue;