From 4a6dec640839a6fba799f1a553934f51dcd977e1 Mon Sep 17 00:00:00 2001
From: Justin Bogner <mail@justinbogner.com>
Date: Wed, 18 Jan 2017 17:29:54 +0000
Subject: [PATCH] GlobalISel: Implement narrowing for G_STORE

Legalize stores of types that are too wide by breaking them up into
sequences of smaller stores.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292412 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/GlobalISel/LegalizerHelper.cpp         | 25 ++++++++++++++++++++--
 .../AArch64/GlobalISel/legalize-load-store.mir     | 12 +++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index eb25b6ca268..bb4f2cf20db 100644
--- a/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -125,6 +125,9 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
   // FIXME: Don't know how to handle secondary types yet.
   if (TypeIdx != 0)
     return UnableToLegalize;
+
+  MIRBuilder.setInstr(MI);
+
   switch (MI.getOpcode()) {
   default:
     return UnableToLegalize;
@@ -134,8 +137,6 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
     int NumParts = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() /
                    NarrowTy.getSizeInBits();
 
-    MIRBuilder.setInstr(MI);
-
     SmallVector<unsigned, 2> Src1Regs, Src2Regs, DstRegs;
     SmallVector<uint64_t, 2> Indexes;
     extractParts(MI.getOperand(1).getReg(), NarrowTy, NumParts, Src1Regs);
@@ -160,6 +161,26 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
     MI.eraseFromParent();
     return Legalized;
   }
+  case TargetOpcode::G_STORE: {
+    unsigned NarrowSize = NarrowTy.getSizeInBits();
+    int NumParts =
+        MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() / NarrowSize;
+    LLT NarrowPtrTy = LLT::pointer(
+        MRI.getType(MI.getOperand(1).getReg()).getAddressSpace(), NarrowSize);
+
+    SmallVector<unsigned, 2> SrcRegs;
+    extractParts(MI.getOperand(0).getReg(), NarrowTy, NumParts, SrcRegs);
+
+    for (int i = 0; i < NumParts; ++i) {
+      unsigned DstReg = MRI.createGenericVirtualRegister(NarrowPtrTy);
+      unsigned Offset = MRI.createGenericVirtualRegister(LLT::scalar(64));
+      MIRBuilder.buildConstant(Offset, i * NarrowSize / 8);
+      MIRBuilder.buildGEP(DstReg, MI.getOperand(1).getReg(), Offset);
+      MIRBuilder.buildStore(SrcRegs[i], DstReg, **MI.memoperands_begin());
+    }
+    MI.eraseFromParent();
+    return Legalized;
+  }
   }
 }
 
diff --git a/test/CodeGen/AArch64/GlobalISel/legalize-load-store.mir b/test/CodeGen/AArch64/GlobalISel/legalize-load-store.mir
index 6a86686fa4b..30636d33f47 100644
--- a/test/CodeGen/AArch64/GlobalISel/legalize-load-store.mir
+++ b/test/CodeGen/AArch64/GlobalISel/legalize-load-store.mir
@@ -62,6 +62,8 @@ registers:
   - { id: 3, class: _ }
   - { id: 4, class: _ }
   - { id: 5, class: _ }
+  - { id: 6, class: _ }
+  - { id: 7, class: _ }
 body: |
   bb.0.entry:
     liveins: %x0, %x1, %x2, %x3
@@ -92,4 +94,14 @@ body: |
 
     ; CHECK: G_STORE %0(p0), %0(p0) :: (store 8 into %ir.addr)
     G_STORE %0(p0), %0(p0) :: (store 8 into %ir.addr)
+
+    ; CHECK: [[OFFSET0:%[0-9]+]](s64) = G_CONSTANT i64 0
+    ; CHECK: [[GEP0:%[0-9]+]](p0) = G_GEP %0, [[OFFSET0]](s64)
+    ; CHECK: G_STORE %5(s64), [[GEP0]](p0) :: (store 16 into %ir.addr)
+    ; CHECK: [[OFFSET1:%[0-9]+]](s64) = G_CONSTANT i64 8
+    ; CHECK: [[GEP1:%[0-9]+]](p0) = G_GEP %0, [[OFFSET1]](s64)
+    ; CHECK: G_STORE %6(s64), [[GEP1]](p0) :: (store 16 into %ir.addr)
+    %6(s64) = G_PTRTOINT %0(p0)
+    %7(s128) = G_SEQUENCE %5, 0, %6, 64
+    G_STORE %7, %0 :: (store 16 into %ir.addr)
 ...
-- 
2.11.0