From aa6cf3803d29f0c129884ff0a1e911dcb3257f97 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dan433584@gmail.com>
Date: Thu, 10 Dec 2015 04:55:31 +0000
Subject: [PATCH] [WebAssembly] Implement mixed-type ISD::FCOPYSIGN.

ISD::FCOPYSIGN permits its operands to have differing types, and DAGCombiner
uses this. Add some def : Pat rules to expand this out into an explicit
conversion and a normal copysign operation.

llvm-svn: 255220
---
 .../WebAssembly/WebAssemblyInstrFloat.td      |  6 ++++
 .../WebAssembly/WebAssemblyInstrInfo.td       |  2 +-
 test/CodeGen/WebAssembly/copysign-casts.ll    | 28 +++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/WebAssembly/copysign-casts.ll

diff --git a/lib/Target/WebAssembly/WebAssemblyInstrFloat.td b/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
index d966380e6b0..5520c6de673 100644
--- a/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
+++ b/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
@@ -38,6 +38,12 @@ defm NEAREST : UnaryFP<fnearbyint, "nearest">;
 
 } // Defs = [ARGUMENTS]
 
+// DAGCombine oddly folds casts into the rhs of copysign. Unfold them.
+def : Pat<(fcopysign F64:$lhs, F32:$rhs),
+          (COPYSIGN_F64 F64:$lhs, (F64_PROMOTE_F32 F32:$rhs))>;
+def : Pat<(fcopysign F32:$lhs, F64:$rhs),
+          (COPYSIGN_F32 F32:$lhs, (F32_DEMOTE_F64 F64:$rhs))>;
+
 // WebAssembly doesn't expose inexact exceptions, so map frint to fnearbyint.
 def : Pat<(frint f32:$src), (NEAREST_F32 f32:$src)>;
 def : Pat<(frint f64:$src), (NEAREST_F64 f64:$src)>;
diff --git a/lib/Target/WebAssembly/WebAssemblyInstrInfo.td b/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
index dafe6c1ed64..5cf8664eba8 100644
--- a/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
+++ b/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
@@ -154,7 +154,7 @@ include "WebAssemblyInstrMemory.td"
 include "WebAssemblyInstrCall.td"
 include "WebAssemblyInstrControl.td"
 include "WebAssemblyInstrInteger.td"
-include "WebAssemblyInstrFloat.td"
 include "WebAssemblyInstrConv.td"
+include "WebAssemblyInstrFloat.td"
 include "WebAssemblyInstrAtomics.td"
 include "WebAssemblyInstrSIMD.td"
diff --git a/test/CodeGen/WebAssembly/copysign-casts.ll b/test/CodeGen/WebAssembly/copysign-casts.ll
new file mode 100644
index 00000000000..0224febb4c0
--- /dev/null
+++ b/test/CodeGen/WebAssembly/copysign-casts.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -asm-verbose=false | FileCheck %s
+
+; DAGCombiner oddly folds casts into the rhs of copysign. Test that they get
+; unfolded.
+
+target datalayout = "e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+declare double @copysign(double, double) nounwind readnone
+declare float @copysignf(float, float) nounwind readnone
+
+; CHECK-LABEL: fold_promote:
+; CHECK: f64.promote/f32 $push0=, $1
+; CHECK: f64.copysign    $push1=, $0, $pop0
+define double @fold_promote(double %a, float %b) {
+  %c = fpext float %b to double
+  %t = call double @copysign(double %a, double %c)
+  ret double %t
+}
+
+; CHECK-LABEL: fold_demote:
+; CHECK: f32.demote/f64  $push0=, $1
+; CHECK: f32.copysign    $push1=, $0, $pop0
+define float @fold_demote(float %a, double %b) {
+  %c = fptrunc double %b to float
+  %t = call float @copysignf(float %a, float %c)
+  ret float %t
+}