[AARCH64] Teach AArch64FrameLowering::getFrameIndexReferencePreferSP really prefer SP.

Do more efforts to use sp if it is possible to lower a frame index.

Reviewers: reames, loicottet, ostannard, t.p.northover
Reviewed By: reames
Subscribers: arphaman, danilaml, hiraditya, kristof.beyls, llvm-commits, Matt, yrouban
Differential Revision: https://reviews.llvm.org/D111133

diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 1dd4f19..b630f4f 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -3537,7 +3537,14 @@ StackOffset AArch64FrameLowering::getFrameIndexReferencePreferSP(
     return StackOffset::getFixed(MFI.getObjectOffset(FI));
   }
 
-  return getFrameIndexReference(MF, FI, FrameReg);
+  // Go to common code if we cannot provide sp + offset.
+  if (MFI.hasVarSizedObjects() ||
+      MF.getInfo<AArch64FunctionInfo>()->getStackSizeSVE() ||
+      MF.getSubtarget().getRegisterInfo()->hasStackRealignment(MF))
+    return getFrameIndexReference(MF, FI, FrameReg);
+
+  FrameReg = AArch64::SP;
+  return getStackOffset(MF, MFI.getObjectOffset(FI));
 }
 
 /// The parent frame offset (aka dispFrame) is only used on X86_64 to retrieve

diff --git a/llvm/test/CodeGen/AArch64/statepoint-call-lowering-sp.ll b/llvm/test/CodeGen/AArch64/statepoint-call-lowering-sp.ll
new file mode 100644 (file)
index 0000000..ed9e718
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/statepoint-call-lowering-sp.ll
@@ -0,0 +1,23 @@
+; RUN: llc -mtriple aarch64-none-linux-gnu -verify-machineinstrs -stop-after=prologepilog < %s | FileCheck %s
+
+; Check that STATEPOINT instruction prefer to use sp in presense of fp.
+target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+declare void @consume(i32 addrspace(1)* %obj)
+
+define i1 @test(i32 addrspace(1)* %a) "frame-pointer"="all" gc "statepoint-example" {
+entry:
+  %safepoint_token = tail call token (i64, i32, i1 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i1f(i64 0, i32 0, i1 ()* @return_i1, i32 0, i32 0, i32 0, i32 0) ["gc-live" (i32 addrspace(1)* %a)]
+; CHECK: STATEPOINT 0, 0, 0, @return_i1, 2, 0, 2, 0, 2, 0, 2, 1, 1, 8, $sp, 24, 2, 0, 2, 1, 0, 0
+  %call1 = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token %safepoint_token,  i32 0, i32 0)
+  %call2 = call zeroext i1 @llvm.experimental.gc.result.i1(token %safepoint_token)
+  call void @consume(i32 addrspace(1)* %call1)
+  ret i1 %call2
+}
+
+
+declare i1 @return_i1()
+declare token @llvm.experimental.gc.statepoint.p0f_i1f(i64, i32, i1 ()*, i32, i32, ...)
+declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token, i32, i32)
+declare i1 @llvm.experimental.gc.result.i1(token)