[PATCH] D35480: [mips] Support `long_call/far/near` attributes passed by front-end

[Simon Atanasyan via Phabricator via llvm-commits]

atanasyan updated this revision to Diff 107287.
atanasyan added a comment.

- Addressed review comments: add 64-bit tests, restore comment in the code.


Repository:
  rL LLVM

https://reviews.llvm.org/D35480

Files:
  lib/Target/Mips/MipsISelLowering.cpp
  test/CodeGen/Mips/long-call-attr.ll


Index: test/CodeGen/Mips/long-call-attr.ll
===================================================================
--- /dev/null
+++ test/CodeGen/Mips/long-call-attr.ll
@@ -0,0 +1,42 @@
+; RUN: llc -march=mips -target-abi o32 --mattr=+long-calls,+noabicalls < %s \
+; RUN:   | FileCheck -check-prefix=O32 %s
+; RUN: llc -march=mips -target-abi o32 --mattr=-long-calls,+noabicalls < %s \
+; RUN:   | FileCheck -check-prefix=O32 %s
+; RUN: llc -march=mips64 -target-abi n64 --mattr=+long-calls,+noabicalls < %s \
+; RUN:   | FileCheck -check-prefix=N64 %s
+; RUN: llc -march=mips64 -target-abi n64 --mattr=-long-calls,+noabicalls < %s \
+; RUN:   | FileCheck -check-prefix=N64 %s
+
+declare void @far() #0
+
+define void @near() #1 {
+  ret void
+}
+
+define void @foo() {
+  call void @far()
+
+; O32-LABEL: foo:
+; O32:         lui     $1, %hi(far)
+; O32-NEXT:    addiu   $25, $1, %lo(far)
+; O32-NEXT:    jalr    $25
+
+; N64-LABEL: foo:
+; N64:         lui     $1, %highest(far)
+; N64-NEXT:    daddiu  $1, $1, %higher(far)
+; N64-NEXT:    dsll    $1, $1, 16
+; N64-NEXT:    daddiu  $1, $1, %hi(far)
+; N64-NEXT:    dsll    $1, $1, 16
+; N64-NEXT:    daddiu  $25, $1, %lo(far)
+; N64-NEXT:    jalr    $25
+
+  call void @near()
+
+; O32:         jal near
+; N64:         jal near
+
+  ret void
+}
+
+attributes #0 = { "long-call" }
+attributes #1 = { "short-call" }
Index: lib/Target/Mips/MipsISelLowering.cpp
===================================================================
--- lib/Target/Mips/MipsISelLowering.cpp
+++ lib/Target/Mips/MipsISelLowering.cpp
@@ -3152,15 +3152,30 @@
   // The long-calls feature is ignored in case of PIC.
   // While we do not support -mshared / -mno-shared properly,
   // ignore long-calls in case of -mabicalls too.
-  if (Subtarget.useLongCalls() && !Subtarget.isABICalls() && !IsPIC) {
-    // Get the address of the callee into a register to prevent
-    // using of the `jal` instruction for the direct call.
-    if (auto *N = dyn_cast<GlobalAddressSDNode>(Callee))
-      Callee = Subtarget.hasSym32() ? getAddrNonPIC(N, SDLoc(N), Ty, DAG)
-                                    : getAddrNonPICSym64(N, SDLoc(N), Ty, DAG);
-    else if (auto *N = dyn_cast<ExternalSymbolSDNode>(Callee))
-      Callee = Subtarget.hasSym32() ? getAddrNonPIC(N, SDLoc(N), Ty, DAG)
-                                    : getAddrNonPICSym64(N, SDLoc(N), Ty, DAG);
+  if (!Subtarget.isABICalls() && !IsPIC) {
+    // If the function should be called using "long call",
+    // get its address into a register to prevent using
+    // of the `jal` instruction for the direct call.
+    if (auto *N = dyn_cast<ExternalSymbolSDNode>(Callee)) {
+      if (Subtarget.useLongCalls())
+        Callee = Subtarget.hasSym32()
+                     ? getAddrNonPIC(N, SDLoc(N), Ty, DAG)
+                     : getAddrNonPICSym64(N, SDLoc(N), Ty, DAG);
+    } else if (auto *N = dyn_cast<GlobalAddressSDNode>(Callee)) {
+      bool UseLongCalls = Subtarget.useLongCalls();
+      // If the function has long-call/far/near attribute
+      // it overrides command line switch pased to the backend.
+      if (auto *F = dyn_cast<Function>(N->getGlobal())) {
+        if (F->hasFnAttribute("long-call"))
+          UseLongCalls = true;
+        else if (F->hasFnAttribute("short-call"))
+          UseLongCalls = false;
+      }
+      if (UseLongCalls)
+        Callee = Subtarget.hasSym32()
+                     ? getAddrNonPIC(N, SDLoc(N), Ty, DAG)
+                     : getAddrNonPICSym64(N, SDLoc(N), Ty, DAG);
+    }
   }
 
   if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {


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