[PATCH] Convert sqrt functions into sqrt instructions when -ffast-math is in effect

[Preston Gurd]

Hi nadav, chandlerc,

When -ffast-math is in effect (on Linux, at least), clang defines __FINITE_MATH_ONLY__ > 0 when including <math.h>. This causes the preprocessor to include <bits/math-finite.h>, which renames the sqrt functions. For instance, "sqrt" is renamed as "__sqrt_finite". 

This patch adds the 3 new names in such a way that they will be treated as equivalent to their respective original names.


http://llvm-reviews.chandlerc.com/D863

Files:
  include/llvm/Target/TargetLibraryInfo.h
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  lib/Target/TargetLibraryInfo.cpp
  test/CodeGen/X86/sqrt-fastmath.ll

Index: include/llvm/Target/TargetLibraryInfo.h
===================================================================
--- include/llvm/Target/TargetLibraryInfo.h
+++ include/llvm/Target/TargetLibraryInfo.h
@@ -57,6 +57,12 @@
       dunder_isoc99_sscanf,
       /// void *__memcpy_chk(void *s1, const void *s2, size_t n, size_t s1size);
       memcpy_chk,
+      /// double __sqrt_finite(double x);
+      sqrt_finite,
+      /// float __sqrt_finite(float x);
+      sqrtf_finite,
+      /// long double __sqrt_finite(long double x);
+      sqrtl_finite,
       /// char * __strdup(const char *s);
       dunder_strdup,
       /// char *__strndup(const char *s, size_t n);
@@ -677,6 +683,8 @@
     case LibFunc::sin:       case LibFunc::sinf:       case LibFunc::sinl:
     case LibFunc::cos:       case LibFunc::cosf:       case LibFunc::cosl:
     case LibFunc::sqrt:      case LibFunc::sqrtf:      case LibFunc::sqrtl:
+    case LibFunc::sqrt_finite: case LibFunc::sqrtf_finite:
+                                                  case LibFunc::sqrtl_finite:
     case LibFunc::floor:     case LibFunc::floorf:     case LibFunc::floorl:
     case LibFunc::nearbyint: case LibFunc::nearbyintf: case LibFunc::nearbyintl:
     case LibFunc::ceil:      case LibFunc::ceilf:      case LibFunc::ceill:
Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5593,6 +5593,9 @@
       case LibFunc::sqrt:
       case LibFunc::sqrtf:
       case LibFunc::sqrtl:
+      case LibFunc::sqrt_finite:
+      case LibFunc::sqrtf_finite:
+      case LibFunc::sqrtl_finite:
         if (visitUnaryFloatCall(I, ISD::FSQRT))
           return;
         break;
Index: lib/Target/TargetLibraryInfo.cpp
===================================================================
--- lib/Target/TargetLibraryInfo.cpp
+++ lib/Target/TargetLibraryInfo.cpp
@@ -43,6 +43,9 @@
     "__isoc99_scanf",
     "__isoc99_sscanf",
     "__memcpy_chk",
+    "__sqrt_finite",
+    "__sqrtf_finite",
+    "__sqrtl_finite",
     "__strdup",
     "__strndup",
     "__strtok_r",
Index: test/CodeGen/X86/sqrt-fastmath.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/sqrt-fastmath.ll
@@ -0,0 +1,60 @@
+; RUN: llc < %s -mcpu=core2 | FileCheck %s
+
+; generated using "clang -S -O2 -ffast-math -emit-llvm sqrt.c" from
+; #include <math.h>
+; 
+; double fd(double d){
+;   return sqrt(d);
+; }
+; 
+; float ff(float f){
+;   return sqrtf(f);
+; }
+; 
+; long double fld(long double ld){
+;   return sqrtl(ld);
+; }
+;
+; Tests conversion of sqrt function calls into sqrt instructions when
+; -ffast-math is in effect.
+
+; ModuleID = 'sqrt.c'
+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-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readnone uwtable
+define double @fd(double %d) #0 {
+entry:
+; CHECK: sqrtsd
+  %call = tail call double @__sqrt_finite(double %d) #2
+  ret double %call
+}
+
+; Function Attrs: nounwind readnone
+declare double @__sqrt_finite(double) #1
+
+; Function Attrs: nounwind readnone uwtable
+define float @ff(float %f) #0 {
+entry:
+; CHECK: sqrtss
+  %call = tail call float @__sqrtf_finite(float %f) #2
+  ret float %call
+}
+
+; Function Attrs: nounwind readnone
+declare float @__sqrtf_finite(float) #1
+
+; Function Attrs: nounwind readnone uwtable
+define x86_fp80 @fld(x86_fp80 %ld) #0 {
+entry:
+; CHECK: fsqrt
+  %call = tail call x86_fp80 @__sqrtl_finite(x86_fp80 %ld) #2
+  ret x86_fp80 %call
+}
+
+; Function Attrs: nounwind readnone
+declare x86_fp80 @__sqrtl_finite(x86_fp80) #1
+
+attributes #0 = { nounwind readnone uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="false" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "unsafe-fp-math"="true" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="false" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "unsafe-fp-math"="true" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D863.1.patch
Type: text/x-patch
Size: 4383 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20130524/4a08b827/attachment.bin>