From 9d06175a15a61b977ebbabd0d9cc738ebfa7870c Mon Sep 17 00:00:00 2001
From: Dale Johannesen <dalej@apple.com>
Date: Fri, 25 Sep 2009 20:54:50 +0000
Subject: [PATCH] Handle sqrt in CannotBeNegativeZero.  absf and absl appear to
 be misspellings, removed in favor of fabs*.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82796 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ValueTracking.cpp            | 10 ++++---
 test/Transforms/InstCombine/no-negzero.ll | 33 +++++++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 test/Transforms/InstCombine/no-negzero.ll

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 9494a2f4c53..baa347a6638 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -840,9 +840,13 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) {
       if (F->isDeclaration()) {
         // abs(x) != -0.0
         if (F->getName() == "abs") return true;
-        // abs[lf](x) != -0.0
-        if (F->getName() == "absf") return true;
-        if (F->getName() == "absl") return true;
+        // fabs[lf](x) != -0.0
+        if (F->getName() == "fabs") return true;
+        if (F->getName() == "fabsf") return true;
+        if (F->getName() == "fabsl") return true;
+        if (F->getName() == "sqrt" || F->getName() == "sqrtf" ||
+            F->getName() == "sqrtl")
+          return CannotBeNegativeZero(CI->getOperand(1), Depth+1);
       }
     }
   
diff --git a/test/Transforms/InstCombine/no-negzero.ll b/test/Transforms/InstCombine/no-negzero.ll
new file mode 100644
index 00000000000..f295130b0ea
--- /dev/null
+++ b/test/Transforms/InstCombine/no-negzero.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; ModuleID = '3555a.c'
+; sqrt(fabs) cannot be negative zero, so we should eliminate the fadd.
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin9.8"
+
+; CHECK: @mysqrt
+; CHECK-NOT: fadd
+; CHECK: ret
+define double @mysqrt(double %x) nounwind {
+entry:
+  %x_addr = alloca double                         ; <double*> [#uses=2]
+  %retval = alloca double, align 8                ; <double*> [#uses=2]
+  %0 = alloca double, align 8                     ; <double*> [#uses=2]
+  %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
+  store double %x, double* %x_addr
+  %1 = load double* %x_addr, align 8              ; <double> [#uses=1]
+  %2 = call double @fabs(double %1) nounwind readnone ; <double> [#uses=1]
+  %3 = call double @sqrt(double %2) nounwind readonly ; <double> [#uses=1]
+  %4 = fadd double %3, 0.000000e+00               ; <double> [#uses=1]
+  store double %4, double* %0, align 8
+  %5 = load double* %0, align 8                   ; <double> [#uses=1]
+  store double %5, double* %retval, align 8
+  br label %return
+
+return:                                           ; preds = %entry
+  %retval1 = load double* %retval                 ; <double> [#uses=1]
+  ret double %retval1
+}
+
+declare double @fabs(double)
+
+declare double @sqrt(double) nounwind readonly
-- 
2.34.1