ARM FastISel integer sext/zext improvements

My recent ARM FastISel patch exposed this bug:
  http://llvm.org/bugs/show_bug.cgi?id=16178
The root cause is that it can't select integer sext/zext pre-ARMv6 and
asserts out.

The current integer sext/zext code doesn't handle other cases gracefully
either, so this patch makes it handle all sext and zext from i1/i8/i16
to i8/i16/i32, with and without ARMv6, both in Thumb and ARM mode. This
should fix the bug as well as make FastISel faster because it bails to
SelectionDAG less often. See fastisel-ext.patch for this.

fastisel-ext-tests.patch changes current tests to always use reg-imm AND
for 8-bit zext instead of UXTB. This simplifies code since it is
supported on ARMv4t and later, and at least on A15 both should perform
exactly the same (both have exec 1 uop 1, type I).

2013-05-31-char-shift-crash.ll is a bitcode version of the above bug
16178 repro.

fast-isel-ext.ll tests all sext/zext combinations that ARM FastISel
should now handle.

Note that my ARM FastISel enabling patch was reverted due to a separate
failure when dealing with MCJIT, I'll fix this second failure and then
turn FastISel on again for non-iOS ARM targets.

I've tested "make check-all" on my x86 box, and "lnt test-suite" on A15
hardware.

llvm-svn: 183551

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/test/CodeGen/ARM/fast-isel-ret.ll b/llvm/test/CodeGen/ARM/fast-isel-ret.ll
index 689b169ee32..4091dc6f6b9 100644
--- a/llvm/test/CodeGen/ARM/fast-isel-ret.ll
+++ b/llvm/test/CodeGen/ARM/fast-isel-ret.ll
@@ -26,7 +26,7 @@ entry:
 define zeroext i8 @ret3(i8 signext %a) nounwind uwtable ssp {
 entry:
 ; CHECK: ret3
-; CHECK: uxtb r0, r0
+; CHECK: and r0, r0, #255
 ; CHECK: bx lr
   ret i8 %a
 }