[PATCH] [LTOCodeGenerator] Iterate over all subtargets when collecting runtime library names that should be protected

[Akira Hatanaka]

Hi echristo, dexonsmith,

Function accumulateAndSortLibcalls in LTOCodeGenerator.cpp collects names of runtime library functions to protect user-supplied runtime library functions (which was committed in r194514). Currently, this function only scans the TargetLowering object belonging to the "main" subtarget for the library function names. This has to be changed to scan all subtargets now that we have per-function subtarget objects.

http://reviews.llvm.org/D7275

Files:
  lib/LTO/LTOCodeGenerator.cpp
  test/LTO/runtime-library-subtarget.ll
  tools/llvm-lto/llvm-lto.cpp

Index: lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- lib/LTO/LTOCodeGenerator.cpp
+++ lib/LTO/LTOCodeGenerator.cpp
@@ -370,8 +370,8 @@
 
 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
                                       const TargetLibraryInfo& TLI,
-                                      const TargetLowering *Lowering)
-{
+                                      const Module &Mod,
+                                      const TargetMachine &TM) {
   // TargetLibraryInfo has info on C runtime library calls on the current
   // target.
   for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
@@ -381,14 +381,21 @@
       Libcalls.push_back(TLI.getName(F));
   }
 
-  // TargetLowering has info on library calls that CodeGen expects to be
-  // available, both from the C runtime and compiler-rt.
-  if (Lowering)
-    for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
-         I != E; ++I)
-      if (const char *Name
-          = Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
-        Libcalls.push_back(Name);
+  SmallPtrSet<const TargetLowering *, 1> TLSet;
+
+  for (const Function &F : Mod) {
+    const TargetLowering *Lowering =
+        TM.getSubtargetImpl(F)->getTargetLowering();
+
+    if (Lowering && TLSet.insert(Lowering).second)
+      // TargetLowering has info on library calls that CodeGen expects to be
+      // available, both from the C runtime and compiler-rt.
+      for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
+           I != E; ++I)
+        if (const char *Name =
+                Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
+          Libcalls.push_back(Name);
+  }
 
   array_pod_sort(Libcalls.begin(), Libcalls.end());
   Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
@@ -412,8 +419,8 @@
   std::vector<StringRef> Libcalls;
   TargetLibraryInfoImpl TLII(Triple(TargetMach->getTargetTriple()));
   TargetLibraryInfo TLI(TLII);
-  accumulateAndSortLibcalls(
-      Libcalls, TLI, TargetMach->getSubtargetImpl()->getTargetLowering());
+
+  accumulateAndSortLibcalls(Libcalls, TLI, *mergedModule, *TargetMach);
 
   for (Module::iterator f = mergedModule->begin(),
          e = mergedModule->end(); f != e; ++f)
Index: test/LTO/runtime-library-subtarget.ll
===================================================================
--- /dev/null
+++ test/LTO/runtime-library-subtarget.ll
@@ -0,0 +1,18 @@
+; Check that user-defined runtime library function __addsf3vfp is not removed
+;
+; RUN: llvm-as <%s >%t1
+; RUN: llvm-lto -o %t2 %t1 -mcpu arm1176jz-s
+; RUN: llvm-nm %t2 | FileCheck %s
+
+target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+target triple = "thumbv7-apple-ios"
+
+; CHECK: ___addsf3vfp
+
+define float @__addsf3vfp(float %a, float %b) #0 {
+entry:
+  %add = fadd float %a, %b
+  ret float %add
+}
+
+attributes #0 = { "target-cpu"="arm1176jzf-s"}
Index: tools/llvm-lto/llvm-lto.cpp
===================================================================
--- tools/llvm-lto/llvm-lto.cpp
+++ tools/llvm-lto/llvm-lto.cpp
@@ -217,6 +217,8 @@
   for (unsigned i = 0; i < KeptDSOSyms.size(); ++i)
     CodeGen.addMustPreserveSymbol(KeptDSOSyms[i].c_str());
 
+  CodeGen.setCpu(MCPU.c_str());
+
   std::string attrs;
   for (unsigned i = 0; i < MAttrs.size(); ++i) {
     if (i > 0)

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