Fix DeleteDeadVarargs not to crash on functions referenced by BlockAddresses

This pass was assuming that if hasAddressTaken() returns false for a
function, the function's only uses are call sites.  That's not true
because there can be references by BlockAddresses too.

Fix the pass to handle this case.  Fix
BlockAddress::replaceUsesOfWithOnConstant() to allow a function's type
to be changed by RAUW'ing the function with a bitcast of the recreated
function.

Patch by Mark Seaborn.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183933 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/test/Transforms/DeadArgElim/2013-05-17-VarargsAndBlockAddress.ll b/test/Transforms/DeadArgElim/2013-05-17-VarargsAndBlockAddress.ll
new file mode 100644
index 0000000..2321603
--- /dev/null
+++ b/test/Transforms/DeadArgElim/2013-05-17-VarargsAndBlockAddress.ll
@@ -0,0 +1,25 @@
+; RUN: opt %s -deadargelim -S | FileCheck %s
+
+
+@block_addr = global i8* blockaddress(@varargs_func, %l1)
+; CHECK: @block_addr = global i8* blockaddress(@varargs_func, %l1)
+
+
+; This function is referenced by a "blockaddress" constant but it is
+; not address-taken, so the pass should be able to remove its unused
+; varargs.
+
+define internal i32 @varargs_func(i8* %addr, ...) {
+  indirectbr i8* %addr, [ label %l1, label %l2 ]
+l1:
+  ret i32 1
+l2:
+  ret i32 2
+}
+; CHECK: define internal i32 @varargs_func(i8* %addr) {
+
+define i32 @caller(i8* %addr) {
+  %r = call i32 (i8*, ...)* @varargs_func(i8* %addr)
+  ret i32 %r
+}
+; CHECK: %r = call i32 @varargs_func(i8* %addr)