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).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188727 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCCTRLoops.cpp b/lib/Target/PowerPC/PPCCTRLoops.cpp
index 05dad8a094dc79704c52dbf7d97b816ebfd74766..d9f132363b15e359ac76419bcbf7b0096de0d51e 100644 (file)
--- a/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/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/test/CodeGen/PowerPC/ctrloop-cpsgn.ll b/test/CodeGen/PowerPC/ctrloop-cpsgn.ll
new file mode 100644 (file)
index 0000000..2f04409
--- /dev/null
+++ b/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
+