Define a maximum supported alignment value for load, store, and
alloca instructions (constrained by their internal encoding),
and add error checking for it. Fix an instcombine bug which
generated huge alignment values (null is infinitely aligned).
This fixes undefined behavior noticed by John Regehr.
llvm-svn: 109643
diff --git a/llvm/lib/VMCore/Instructions.cpp b/llvm/lib/VMCore/Instructions.cpp
index 57b7f3f..e03cc82 100644
--- a/llvm/lib/VMCore/Instructions.cpp
+++ b/llvm/lib/VMCore/Instructions.cpp
@@ -891,6 +891,8 @@
void AllocaInst::setAlignment(unsigned Align) {
assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
+ assert(Align <= MaximumAlignment &&
+ "Alignment is greater than MaximumAlignment!");
setInstructionSubclassData(Log2_32(Align) + 1);
assert(getAlignment() == Align && "Alignment representation error!");
}
@@ -1026,8 +1028,11 @@
void LoadInst::setAlignment(unsigned Align) {
assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
+ assert(Align <= MaximumAlignment &&
+ "Alignment is greater than MaximumAlignment!");
setInstructionSubclassData((getSubclassDataFromInstruction() & 1) |
((Log2_32(Align)+1)<<1));
+ assert(getAlignment() == Align && "Alignment representation error!");
}
//===----------------------------------------------------------------------===//
@@ -1122,8 +1127,11 @@
void StoreInst::setAlignment(unsigned Align) {
assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
+ assert(Align <= MaximumAlignment &&
+ "Alignment is greater than MaximumAlignment!");
setInstructionSubclassData((getSubclassDataFromInstruction() & 1) |
((Log2_32(Align)+1) << 1));
+ assert(getAlignment() == Align && "Alignment representation error!");
}
//===----------------------------------------------------------------------===//