Fix memcmp code-gen to honor -fno-builtin.

I noticed that SelectionDAGBuilder::visitCall was missing a check for memcmp
in TargetLibraryInfo, so that it would use custom code for memcmp calls even
with -fno-builtin.  I also had to add a new -disable-simplify-libcalls option
to llc so that I could write a test for this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161262 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 2cdc41b078e89983c8658a2bf368487aa3134365..692c437689427c5d6dcc248f59af41c8e356b05a 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5682,7 +5682,7 @@ void SelectionDAGBuilder::visitCall(const CallInst &I) {
                                    Tmp.getValueType(), Tmp));
           return;
         }
-      } else if (Name == "memcmp") {
+      } else if ((LibInfo->has(LibFunc::memcmp) && Name == "memcmp")) {
         if (visitMemCmpCall(I))
           return;
       }

diff --git a/test/CodeGen/X86/memcmp.ll b/test/CodeGen/X86/memcmp.ll
index f4bc1bb7015a0555ba025608002d2703c9352f2c..723d1d89427ee261c6e055bdef05da3108477ea0 100644 (file)
--- a/test/CodeGen/X86/memcmp.ll
+++ b/test/CodeGen/X86/memcmp.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s
+; RUN: llc < %s -disable-simplify-libcalls -mtriple=x86_64-linux | FileCheck %s --check-prefix=NOBUILTIN
 ; RUN: llc < %s -mtriple=x86_64-win32 | FileCheck %s
 
 ; This tests codegen time inlining/optimization of memcmp
@@ -23,6 +24,8 @@ return:                                           ; preds = %entry
 ; CHECK: memcmp2:
 ; CHECK: movw    ([[A0:%rdi|%rcx]]), %ax
 ; CHECK: cmpw    ([[A1:%rsi|%rdx]]), %ax
+; NOBUILTIN: memcmp2:
+; NOBUILTIN: callq
 }
 
 define void @memcmp2a(i8* %X, i32* nocapture %P) nounwind {

diff --git a/tools/llc/llc.cpp b/tools/llc/llc.cpp
index 004763f19fa8c879a6e95397a20892e8f76f5957..8951050c07cddf70f6df87740ac409d275b2851e 100644 (file)
--- a/tools/llc/llc.cpp
+++ b/tools/llc/llc.cpp
@@ -35,6 +35,7 @@
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Target/TargetMachine.h"
 #include <memory>
 using namespace llvm;
@@ -213,6 +214,11 @@ DontPlaceZerosInBSS("nozero-initialized-in-bss",
   cl::desc("Don't place zero-initialized symbols into bss section"),
   cl::init(false));
 
+static cl::opt<bool>
+DisableSimplifyLibCalls("disable-simplify-libcalls",
+  cl::desc("Disable simplify-libcalls"),
+  cl::init(false));
+
 static cl::opt<bool>
 EnableGuaranteedTailCallOpt("tailcallopt",
   cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
@@ -487,6 +493,12 @@ int main(int argc, char **argv) {
   // Build up all of the passes that we want to do to the module.
   PassManager PM;
 
+  // Add an appropriate TargetLibraryInfo pass for the module's triple.
+  TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
+  if (DisableSimplifyLibCalls)
+    TLI->disableAllFunctions();
+  PM.add(TLI);
+
   // Add the target data from the target machine, if it exists, or the module.
   if (const TargetData *TD = Target.getTargetData())
     PM.add(new TargetData(*TD));