After 077bff39d4,
isDereferenceableForAllocaSize() can recurse into selects,
which is causing a problem for the new test case,
reduced from https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20210412/904154.html
because the replacement (the select) is defined after the first use
of an alloca, so we'd end up with a verifier error.
Now, this new check is too restrictive.
We likely can handle *some* cases, by trying to sink all uses of an alloca
to after the the def.
I think we can use here same logic as for nonnull.
strlen(X) - X must be noundef => valid pointer.
for libcalls with size arg, we add noundef only if size is known and greater than 0 - so pointers must be noundef (valid ones)
Reviewed By: jdoerfert, aqjune
Differential Revision: https://reviews.llvm.org/D95122
This was broken by 16295d521e, when
instructions started being handled and not just constant
expressions. This was re-inserting an equivalent bitcast to the
original memcpy operand, which made a non-functional IR change on
every iteration.
This also fixes a secondary problem where it was inserting
addrspacecasts which may not have been legal (i.e. it changed the
source address space). Start visiting all pointer users and fail out
if we can't process them. Also start handling the relevant memory
intrinsic users. These cases can be dealt with by running
InferAddressSpaces separately.
The langref already states it does, but this wasn't implemented. Also
covers inalloca and preallocated. Also helps fix a dependence on
pointer element types.
Consider any constant memory type, not just global constants. AMDGPU
kernel parameters are effectively global constants, but appear as
either reads from an intrinsic derived pointer or function argument.
Roman Lebedev