[ARM] Reapply r296865 "[ARM] fpscr read/write intrinsics not aware of each other""

The original patch r296865 was reverted as it broke the chromium builds for
Android https://bugs.llvm.org/show_bug.cgi?id=32134, this patch reapplies
r296865 with a fix to make sure it doesn't cause the build regression.

The problem was that intrinsic selection on int_arm_get_fpscr was failing in
ISel this was because the code to manually select this intrinsic still thought
it was the version with no side-effects (INTRINSIC_WO_CHAIN) which is wrong as
it doesn't semantically match the definition in the tablegen code which says it
does have side-effects, I've fixed this by updating the intrinsic type to
INTRINSIC_W_CHAIN (has side-effects). I've also added a test for this based on
Hans original reproducer.

Differential Revision: https://reviews.llvm.org/D30645

llvm-svn: 297137

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 4b6d0e1a34b..6d735a3bed0 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -4913,9 +4913,10 @@ SDValue ARMTargetLowering::LowerFLT_ROUNDS_(SDValue Op,
   // The formula we use to implement this is (((FPSCR + 1 << 22) >> 22) & 3)
   // so that the shift + and get folded into a bitfield extract.
   SDLoc dl(Op);
-  SDValue FPSCR = DAG.getNode(ISD::INTRINSIC_WO_CHAIN, dl, MVT::i32,
-                              DAG.getConstant(Intrinsic::arm_get_fpscr, dl,
-                                              MVT::i32));
+  SDValue Ops[] = { DAG.getEntryNode(),
+                    DAG.getConstant(Intrinsic::arm_get_fpscr, dl, MVT::i32) };
+
+  SDValue FPSCR = DAG.getNode(ISD::INTRINSIC_W_CHAIN, dl, MVT::i32, Ops);
   SDValue FltRounds = DAG.getNode(ISD::ADD, dl, MVT::i32, FPSCR,
                                   DAG.getConstant(1U << 22, dl, MVT::i32));
   SDValue RMODE = DAG.getNode(ISD::SRL, dl, MVT::i32, FltRounds,