From 8f0bf6c19af03da36dbcca969f3500fdd4619df9 Mon Sep 17 00:00:00 2001
From: Daniel Cederman <cederman@gaisler.com>
Date: Thu, 30 Aug 2018 14:05:26 +0000
Subject: [PATCH] [Sparc] Use ANDN instead of AND if constant can be encoded
 more efficiently

Summary:
In the case of (and reg, constant) or (or reg, constant), it can be
beneficial to use a ANDNrr/ORNrr instruction instead of ANDrr/ORrr,
if the complement of the constant can be encoded using a single SETHI
instruction instead of a SETHI/ORri pair.

If the constant has more than one use, it is probably better to keep it
in its original form.

Reviewers: jyknight, venkatra

Reviewed By: jyknight

Subscribers: fedor.sergeev, jrtc27, llvm-commits

Differential Revision: https://reviews.llvm.org/D50964

llvm-svn: 341069
---
 llvm/lib/Target/Sparc/SparcInstrInfo.td | 18 +++++++++++
 llvm/test/CodeGen/SPARC/sethiandn.ll    | 42 +++++++++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 llvm/test/CodeGen/SPARC/sethiandn.ll

diff --git a/llvm/lib/Target/Sparc/SparcInstrInfo.td b/llvm/lib/Target/Sparc/SparcInstrInfo.td
index 5b7fb3c485e8..1c1197f100a0 100644
--- a/llvm/lib/Target/Sparc/SparcInstrInfo.td
+++ b/llvm/lib/Target/Sparc/SparcInstrInfo.td
@@ -89,10 +89,22 @@ def HI22 : SDNodeXForm<imm, [{
                                    MVT::i32);
 }]>;
 
+// Return the complement of a HI22 immediate value.
+def HI22_not : SDNodeXForm<imm, [{
+  return CurDAG->getTargetConstant(~(unsigned)N->getZExtValue() >> 10, SDLoc(N),
+                                   MVT::i32);
+}]>;
+
 def SETHIimm : PatLeaf<(imm), [{
   return isShiftedUInt<22, 10>(N->getZExtValue());
 }], HI22>;
 
+// The N->hasOneUse() prevents the immediate from being instantiated in both
+// normal and complement form.
+def SETHIimm_not : PatLeaf<(i32 imm), [{
+  return N->hasOneUse() && isShiftedUInt<22, 10>(~(unsigned)N->getZExtValue());
+}], HI22_not>;
+
 // Addressing modes.
 def ADDRrr : ComplexPattern<iPTR, 2, "SelectADDRrr", [], []>;
 def ADDRri : ComplexPattern<iPTR, 2, "SelectADDRri", [frameindex], []>;
@@ -680,6 +692,12 @@ def XNORri  : F3_2<2, 0b000111,
                    (outs IntRegs:$rd), (ins IntRegs:$rs1, simm13Op:$simm13),
                    "xnor $rs1, $simm13, $rd", []>;
 
+def : Pat<(and IntRegs:$rs1, SETHIimm_not:$rs2),
+          (ANDNrr i32:$rs1, (SETHIi SETHIimm_not:$rs2))>;
+
+def : Pat<(or IntRegs:$rs1, SETHIimm_not:$rs2),
+          (ORNrr i32:$rs1,  (SETHIi SETHIimm_not:$rs2))>;
+
 let Defs = [ICC] in {
   defm ANDCC  : F3_12np<"andcc",  0b010001>;
   defm ANDNCC : F3_12np<"andncc", 0b010101>;
diff --git a/llvm/test/CodeGen/SPARC/sethiandn.ll b/llvm/test/CodeGen/SPARC/sethiandn.ll
new file mode 100644
index 000000000000..b83c9830e498
--- /dev/null
+++ b/llvm/test/CodeGen/SPARC/sethiandn.ll
@@ -0,0 +1,42 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=sparc | FileCheck %s -check-prefix=SPARC
+
+define i32 @test_andn(i32 %x) nounwind {
+; SPARC-LABEL: test_andn:
+; SPARC:       ! %bb.0: ! %entry
+; SPARC-NEXT:    sethi 4194272, %o1
+; SPARC-NEXT:    retl
+; SPARC-NEXT:    andn %o0, %o1, %o0
+entry:
+  %and = and i32 %x, 32767
+  ret i32 %and
+}
+
+define i32 @test_orn(i32 %x) nounwind {
+; SPARC-LABEL: test_orn:
+; SPARC:       ! %bb.0: ! %entry
+; SPARC-NEXT:    sethi 4194272, %o1
+; SPARC-NEXT:    retl
+; SPARC-NEXT:    orn %o0, %o1, %o0
+entry:
+  %or = or i32 %x, 32767
+  ret i32 %or
+}
+
+; If constant is used more than once it is probably
+; better to keep it in its original form.
+define i32 @test_used_more_than_once(i32 %x) nounwind {
+; SPARC-LABEL: test_used_more_than_once:
+; SPARC:       ! %bb.0: ! %entry
+; SPARC-NEXT:    sethi 31, %o1
+; SPARC-NEXT:    or %o1, 1023, %o1
+; SPARC-NEXT:    or %o0, %o1, %o2
+; SPARC-NEXT:    and %o0, %o1, %o0
+; SPARC-NEXT:    retl
+; SPARC-NEXT:    xor %o2, %o0, %o0
+entry:
+  %0 = or i32 %x, 32767
+  %and = and i32 %x, 32767
+  %res = xor i32 %0, %and
+  ret i32 %res
+}