Avoid symbol name clash when filling TOC.

Patch by Adhemerval Zanella.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164141 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 42 insertions, 3 deletions

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index 23652f00d0..5a8830cb66 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -183,6 +183,7 @@ namespace llvm {
 
     /// LookupSymbol - Get the symbol for \p Name, or null.
     MCSymbol *LookupSymbol(StringRef Name) const;
+    MCSymbol *LookupSymbol(const Twine &Name) const;
 
     /// getSymbols - Get a reference for the symbol table for clients that
     /// want to, for example, iterate over all symbols. 'const' because we
diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index b5b14b95f6..477bd17c0d 100644
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -153,6 +153,12 @@ MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
   return Symbols.lookup(Name);
 }
 
+MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
+  SmallString<128> NameSV;
+  Name.toVector(NameSV);
+  return LookupSymbol(NameSV.str());
+}
+
 //===----------------------------------------------------------------------===//
 // Section Management
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index ee35ee5a5b..a66677fa0f 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -368,9 +368,14 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     else if (MO.isJTI())
       MOSymbol = GetJTISymbol(MO.getIndex());
     MCSymbol *&TOCEntry = TOC[MOSymbol];
-    if (TOCEntry == 0)
-      TOCEntry = GetTempSymbol("C", TOCLabelID++);
-    
+    // To avoid name clash check if the name already exists.
+    while (TOCEntry == 0) {
+      if (OutContext.LookupSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
+                                  "C" + Twine(TOCLabelID++)) == 0) {
+        TOCEntry = GetTempSymbol("C", TOCLabelID);
+      }
+    }
+
     const MCExpr *Exp =
       MCSymbolRefExpr::Create(TOCEntry, MCSymbolRefExpr::VK_PPC_TOC_ENTRY,
                               OutContext);
diff --git a/test/CodeGen/PowerPC/2012-09-16-TOC-entry-check.ll b/test/CodeGen/PowerPC/2012-09-16-TOC-entry-check.ll
new file mode 100644
index 0000000000..9d2e390c1c
--- /dev/null
+++ b/test/CodeGen/PowerPC/2012-09-16-TOC-entry-check.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+; This test check if the TOC entry symbol name won't clash with global .LC0
+; and .LC2 symbols defined in the module.
+
+@.LC0 = internal global [5 x i8] c".LC0\00"
+@.LC2 = internal global [5 x i8] c".LC2\00"
+
+define i32 @foo(double %X, double %Y) nounwind readnone {
+  ; The 1.0 and 3.0 constants generate two TOC entries
+  %cmp = fcmp oeq double %X, 1.000000e+00
+  %conv = zext i1 %cmp to i32
+  %cmp1 = fcmp oeq double %Y, 3.000000e+00
+  %conv2 = zext i1 %cmp1 to i32
+  %add = add nsw i32 %conv2, %conv
+  ret i32 %add
+}
+
+; Check the creation of 2 .tc entries for both double constants. They
+; should be .LC1 and .LC3 to avoid name clash with global constants
+; .LC0 and .LC2
+; CHECK: .LC{{[13]}}:
+; CHECK-NEXT: .tc {{[\._a-zA-Z0-9]+}}[TC],{{[\._a-zA-Z0-9]+}}
+; CHECK: .LC{{[13]}}:
+; CHECK-NEXT: .tc {{[\._a-zA-Z0-9]+}}[TC],{{[\._a-zA-Z0-9]+}}