From 1cf48ab811b341cf2ee3d7e9a9c97cf2d7b53f64 Mon Sep 17 00:00:00 2001
From: Hal Finkel <hfinkel@anl.gov>
Date: Mon, 19 Aug 2013 23:35:24 +0000
Subject: [PATCH] Don't form PPC CTR-based loops around a copysignl call

copysign/copysignf never become function calls (because the SDAG expansion code
does not lower to the corresponding function call, but rather directly
implements the associated logic), but copysignl almost always is lowered into a
call to the requested libm functon (and, thus, might clobber CTR).

llvm-svn: 188727
---
 llvm/lib/Target/PowerPC/PPCCTRLoops.cpp    |  3 ++-
 llvm/test/CodeGen/PowerPC/ctrloop-cpsgn.ll | 28 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/PowerPC/ctrloop-cpsgn.ll

diff --git a/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp b/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
index 05dad8a094dc..d9f132363b15 100644
--- a/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -284,8 +284,9 @@ bool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) {
           default: return true;
           case LibFunc::copysign:
           case LibFunc::copysignf:
-          case LibFunc::copysignl:
             continue; // ISD::FCOPYSIGN is never a library call.
+          case LibFunc::copysignl:
+            return true;
           case LibFunc::fabs:
           case LibFunc::fabsf:
           case LibFunc::fabsl:
diff --git a/llvm/test/CodeGen/PowerPC/ctrloop-cpsgn.ll b/llvm/test/CodeGen/PowerPC/ctrloop-cpsgn.ll
new file mode 100644
index 000000000000..2f0440912cc9
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/ctrloop-cpsgn.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mcpu=ppc | FileCheck %s
+
+target datalayout = "E-p:32:32:32-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"
+target triple = "powerpc-unknown-linux-gnu"
+
+define ppc_fp128 @foo(ppc_fp128* nocapture %n, ppc_fp128 %d) nounwind readonly {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %x.05 = phi ppc_fp128 [ %d, %entry ], [ %conv, %for.body ]
+  %arrayidx = getelementptr inbounds ppc_fp128* %n, i32 %i.06
+  %0 = load ppc_fp128* %arrayidx, align 8
+  %conv = tail call ppc_fp128 @copysignl(ppc_fp128 %x.05, ppc_fp128 %d) nounwind readonly
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, 2048
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret ppc_fp128 %conv
+}
+
+declare ppc_fp128 @copysignl(ppc_fp128, ppc_fp128) #0
+
+; CHECK: @foo
+; CHECK-NOT: mtctr
+