Use function attribute "trap-func-name" and remove TargetOptions::TrapFuncName.

This commit changes normal isel and fast isel to read the user-defined trap
function name from function attribute "trap-func-name" attached to llvm.trap or
llvm.debugtrap instead of from TargetOptions::TrapFuncName. This is needed to
use clang's command line option "-ftrap-function" for LTO and enable changing
the trap function name on a per-call-site basis.

Out-of-tree projects currently using TargetOptions::TrapFuncName to specify the
trap function name should attach attribute "trap-func-name" to the call sites
of llvm.trap and llvm.debugtrap instead.

rdar://problem/21225723

Differential Revision: http://reviews.llvm.org/D10832


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241305 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/ARM/fnattr-trap.ll

@@ -0,0 +1,40 @@
+; RUN: llc < %s -march arm | FileCheck %s -check-prefix=NOOPTION
+; RUN: llc < %s -march arm -trap-func=trap_llc | FileCheck %s -check-prefix=TRAP
+
+; NOOPTION-LABEL: {{\_?}}foo0:
+; NOOPTION: trap{{$}}
+
+; TRAP-LABEL: {{\_?}}foo0:
+; TRAP: bl {{\_?}}trap_llc
+
+define void @foo0() {
+  call void @llvm.trap()
+  unreachable
+}
+
+; NOOPTION-LABEL: {{\_?}}foo1:
+; NOOPTION: bl {{\_?}}trap_func_attr0
+
+; TRAP-LABEL: {{\_?}}foo1:
+; TRAP: bl {{\_?}}trap_llc
+
+define void @foo1() {
+  call void @llvm.trap() #0
+  unreachable
+}
+
+; NOOPTION-LABEL: {{\_?}}foo2:
+; NOOPTION: bl {{\_?}}trap_func_attr1
+
+; TRAP-LABEL: {{\_?}}foo2:
+; TRAP: bl {{\_?}}trap_llc
+
+define void @foo2() {
+  call void @llvm.trap() #1
+  unreachable
+}
+
+declare void @llvm.trap() nounwind
+
+attributes #0 = { "trap-func-name"="trap_func_attr0" }
+attributes #1 = { "trap-func-name"="trap_func_attr1" }