[WebAssembly] Don't expand divisions by constants.

Don't expand divisions by constants if it would require multiple instructions.
The current assumption is that engines will perform the desired optimizations.

llvm-svn: 269930

2 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index d43bf1ab8ec..faaeff08593 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -243,6 +243,12 @@ bool WebAssemblyTargetLowering::allowsMisalignedMemoryAccesses(
   return true;
 }
 
+bool WebAssemblyTargetLowering::isIntDivCheap(EVT VT, AttributeSet Attr) const {
+  // The current thinking is that wasm engines will perform this optimization,
+  // so we can save on code size.
+  return true;
+}
+
 //===----------------------------------------------------------------------===//
 // WebAssembly Lowering private implementation.
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
index 5b538fda479..e5d2fa43ad4 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h
@@ -58,6 +58,7 @@ class WebAssemblyTargetLowering final : public TargetLowering {
                              unsigned AS) const override;
   bool allowsMisalignedMemoryAccesses(EVT, unsigned AddrSpace, unsigned Align,
                                       bool *Fast) const override;
+  bool isIntDivCheap(EVT VT, AttributeSet Attr) const override;
 
   SDValue LowerCall(CallLoweringInfo &CLI,
                     SmallVectorImpl<SDValue> &InVals) const override;