Merge commit '6e5b23504e18' from apple/stable/20200714 into swift/main

Author: git apple-llvm automerger

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -4907,6 +4907,9 @@ bool InstCombiner::transformConstExprCastCall(CallBase &Call) {
     if (Call.isInAllocaArgument(i))
       return false;   // Cannot transform to and from inalloca.
 
+    if (CallerPAL.hasParamAttribute(i, Attribute::SwiftError))
+      return false;
+
     // If the parameter is passed as a byval argument, then we have to have a
     // sized type and the sized type has to have the same size as the old type.
     if (ParamTy != ActTy && CallerPAL.hasParamAttribute(i, Attribute::ByVal)) {

llvm/test/Transforms/InstCombine/swifterror-argument-bitcast-fold.ll

@@ -0,0 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -instcombine -S %s | FileCheck %s
+
+; The swifterror value can only be loaded, stored or used as swifterror
+; argument. Make sure we do not try to turn the function bitcast into an
+; argument bitcast.
+define swiftcc void @spam(i32** swifterror %arg) {
+; CHECK-LABEL: @spam(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    call swiftcc void bitcast (void (i64**)* @widget to void (i32**)*)(i32** swifterror [[ARG:%.*]])
+; CHECK-NEXT:    ret void
+;
+bb:
+  call swiftcc void bitcast (void (i64**)* @widget to void (i32**)*)(i32** swifterror %arg)
+  ret void
+}
+
+declare swiftcc void @widget(i64**)