[WebAssembly] Fold setne and seteq comparisons into selects.

llvm-svn: 254104

2 files changed, 28 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrFloat.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
index a24c8bfdef3..0d819581621 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrFloat.td
@@ -73,3 +73,17 @@ def SELECT_F64 : I<(outs F64:$dst), (ins I32:$cond, F64:$lhs, F64:$rhs),
                    "f64.select\t$dst, $cond, $lhs, $rhs">;
 
 } // Defs = [ARGUMENTS]
+
+// ISD::SELECT requires its operand to conform to getBooleanContents, but
+// WebAssembly's select interprets any non-zero value as true, so we can fold
+// a setne with 0 into a select.
+def : Pat<(select (i32 (setne I32:$cond, 0)), F32:$lhs, F32:$rhs),
+          (SELECT_F32 I32:$cond, F32:$lhs, F32:$rhs)>;
+def : Pat<(select (i32 (setne I32:$cond, 0)), F64:$lhs, F64:$rhs),
+          (SELECT_F64 I32:$cond, F64:$lhs, F64:$rhs)>;
+
+// And again, this time with seteq instead of setne and the arms reversed.
+def : Pat<(select (i32 (seteq I32:$cond, 0)), F32:$lhs, F32:$rhs),
+          (SELECT_F32 I32:$cond, F32:$rhs, F32:$lhs)>;
+def : Pat<(select (i32 (seteq I32:$cond, 0)), F64:$lhs, F64:$rhs),
+          (SELECT_F64 I32:$cond, F64:$rhs, F64:$lhs)>;
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td
index bc00cd6b4f7..3fa2f712034 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInteger.td
@@ -63,3 +63,17 @@ def SELECT_I64 : I<(outs I64:$dst), (ins I32:$cond, I64:$lhs, I64:$rhs),
                    "i64.select\t$dst, $cond, $lhs, $rhs">;
 
 } // Defs = [ARGUMENTS]
+
+// ISD::SELECT requires its operand to conform to getBooleanContents, but
+// WebAssembly's select interprets any non-zero value as true, so we can fold
+// a setne with 0 into a select.
+def : Pat<(select (i32 (setne I32:$cond, 0)), I32:$lhs, I32:$rhs),
+          (SELECT_I32 I32:$cond, I32:$lhs, I32:$rhs)>;
+def : Pat<(select (i32 (setne I32:$cond, 0)), I64:$lhs, I64:$rhs),
+          (SELECT_I64 I32:$cond, I64:$lhs, I64:$rhs)>;
+
+// And again, this time with seteq instead of setne and the arms reversed.
+def : Pat<(select (i32 (seteq I32:$cond, 0)), I32:$lhs, I32:$rhs),
+          (SELECT_I32 I32:$cond, I32:$rhs, I32:$lhs)>;
+def : Pat<(select (i32 (seteq I32:$cond, 0)), I64:$lhs, I64:$rhs),
+          (SELECT_I64 I32:$cond, I64:$rhs, I64:$lhs)>;