commit 74c83649547c270106ceaeb50ac9317ad17d0621
author Lewis Revill <lewis.revill@embecosm.com> Tue Jun 18 14:29:45 2019 +0000
committer Lewis Revill <lewis.revill@embecosm.com> Tue Jun 18 14:29:45 2019 +0000
tree f08669308f3efbdda13773b0ee4a056e0f8bdfbe
parent 2fef12ccb1967b3a53a59511159d2b267298f708

[RISCV] Lower calls through PLT

This patch adds support for generating calls through the procedure
linkage table where required for a given ExternalSymbol or GlobalAddress
callee.

Differential Revision: https://reviews.llvm.org/D55304

llvm-svn: 363686

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 363f815..45217f6 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -1921,11 +1921,21 @@
   // TargetGlobalAddress/TargetExternalSymbol node so that legalize won't
   // split it and then direct call can be matched by PseudoCALL.
   if (GlobalAddressSDNode *S = dyn_cast<GlobalAddressSDNode>(Callee)) {
-    Callee = DAG.getTargetGlobalAddress(S->getGlobal(), DL, PtrVT, 0,
-                                        RISCVII::MO_CALL);
+    const GlobalValue *GV = S->getGlobal();
+
+    unsigned OpFlags = RISCVII::MO_CALL;
+    if (!getTargetMachine().shouldAssumeDSOLocal(*GV->getParent(), GV))
+      OpFlags = RISCVII::MO_PLT;
+
+    Callee = DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0, OpFlags);
   } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
-    Callee =
-        DAG.getTargetExternalSymbol(S->getSymbol(), PtrVT, RISCVII::MO_CALL);
+    unsigned OpFlags = RISCVII::MO_CALL;
+
+    if (!getTargetMachine().shouldAssumeDSOLocal(*MF.getFunction().getParent(),
+                                                 nullptr))
+      OpFlags = RISCVII::MO_PLT;
+
+    Callee = DAG.getTargetExternalSymbol(S->getSymbol(), PtrVT, OpFlags);
   }
 
   // The first call operand is the chain and the second is the target address.

llvm/lib/Target/RISCV/RISCVMCInstLower.cpp

diff --git a/llvm/lib/Target/RISCV/RISCVMCInstLower.cpp b/llvm/lib/Target/RISCV/RISCVMCInstLower.cpp
index dc35944..b40eaa9 100644
--- a/llvm/lib/Target/RISCV/RISCVMCInstLower.cpp
+++ b/llvm/lib/Target/RISCV/RISCVMCInstLower.cpp
@@ -39,6 +39,9 @@
   case RISCVII::MO_CALL:
     Kind = RISCVMCExpr::VK_RISCV_CALL;
     break;
+  case RISCVII::MO_PLT:
+    Kind = RISCVMCExpr::VK_RISCV_CALL_PLT;
+    break;
   case RISCVII::MO_LO:
     Kind = RISCVMCExpr::VK_RISCV_LO;
     break;

llvm/lib/Target/RISCV/Utils/RISCVBaseInfo.h

diff --git a/llvm/lib/Target/RISCV/Utils/RISCVBaseInfo.h b/llvm/lib/Target/RISCV/Utils/RISCVBaseInfo.h
index 09bbfd2..490f64e 100644
--- a/llvm/lib/Target/RISCV/Utils/RISCVBaseInfo.h
+++ b/llvm/lib/Target/RISCV/Utils/RISCVBaseInfo.h
@@ -49,6 +49,7 @@
 enum {
   MO_None,
   MO_CALL,
+  MO_PLT,
   MO_LO,
   MO_HI,
   MO_PCREL_LO,