[WebAssembly] Add an option to make get_local/set_local explicit.

This patch adds a pass, controlled by an option and off by default for
now, for making implicit get_local/set_local explicit. This simplifies
emitting wasm with MC.

Differential Revision: https://reviews.llvm.org/D25836

llvm-svn: 285009

1 files changed, 50 insertions, 18 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
index a316a74fdd2..f774e90d22f 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td
@@ -71,6 +71,9 @@ let OperandNamespace = "WebAssembly" in {
 let OperandType = "OPERAND_BASIC_BLOCK" in
 def bb_op : Operand<OtherVT>;
 
+let OperandType = "OPERAND_LOCAL" in
+def local_op : Operand<i32>;
+
 let OperandType = "OPERAND_I32IMM" in
 def i32imm_op : Operand<i32>;
 
@@ -133,20 +136,42 @@ let Defs = [ARGUMENTS] in {
 // are implied by virtual register uses and defs.
 multiclass LOCAL<WebAssemblyRegClass vt> {
 let hasSideEffects = 0 in {
-  // COPY_LOCAL is not an actual instruction in wasm, but since we allow
-  // get_local and set_local to be implicit, we can have a COPY_LOCAL which
-  // is actually a no-op because all the work is done in the implied
-  // get_local and set_local.
-  let isAsCheapAsAMove = 1 in
-  def COPY_LOCAL_#vt : I<(outs vt:$res), (ins vt:$src), [],
-                         "copy_local\t$res, $src">;
-
-  // TEE_LOCAL is similar to COPY_LOCAL, but writes two copies of its result.
-  // Typically this would be used to stackify one result and write the other
-  // result to a local.
-  let isAsCheapAsAMove = 1 in
-  def TEE_LOCAL_#vt : I<(outs vt:$res, vt:$also), (ins vt:$src), [],
-                        "tee_local\t$res, $also, $src">;
+  // COPY is not an actual instruction in wasm, but since we allow get_local and
+  // set_local to be implicit during most of codegen, we can have a COPY which
+  // is actually a no-op because all the work is done in the implied get_local
+  // and set_local. COPYs are eliminated (and replaced with
+  // get_local/set_local) in the ExplicitLocals pass.
+  let isAsCheapAsAMove = 1, isCodeGenOnly = 1 in
+  def COPY_#vt : I<(outs vt:$res), (ins vt:$src), [], "copy_local\t$res, $src">;
+
+  // TEE is similar to COPY, but writes two copies of its result. Typically
+  // this would be used to stackify one result and write the other result to a
+  // local.
+  let isAsCheapAsAMove = 1, isCodeGenOnly = 1 in
+  def TEE_#vt : I<(outs vt:$res, vt:$also), (ins vt:$src), [],
+                  "tee_local\t$res, $also, $src">;
+
+  // This is the actual get_local instruction in wasm. These are made explicit
+  // by the ExplicitLocals pass. It has mayLoad because it reads from a wasm
+  // local, which is a side effect not otherwise modeled in LLVM.
+  let mayLoad = 1, isAsCheapAsAMove = 1 in
+  def GET_LOCAL_#vt : I<(outs vt:$res), (ins local_op:$local), [],
+                        "get_local\t$res, $local", 0x14>;
+
+  // This is the actual set_local instruction in wasm. These are made explicit
+  // by the ExplicitLocals pass. It has mayStore because it writes to a wasm
+  // local, which is a side effect not otherwise modeled in LLVM.
+  let mayStore = 1, isAsCheapAsAMove = 1 in
+  def SET_LOCAL_#vt : I<(outs), (ins local_op:$local, vt:$src), [],
+                        "set_local\t$local, $src", 0x15>;
+
+  // This is the actual tee_local instruction in wasm. TEEs are turned into
+  // TEE_LOCALs by the ExplicitLocals pass. It has mayStore for the same reason
+  // as SET_LOCAL.
+  let mayStore = 1, isAsCheapAsAMove = 1 in
+  def TEE_LOCAL_#vt : I<(outs vt:$res), (ins local_op:$local, vt:$src), [],
+                         "tee_local\t$res, $local, $src", 0x19>;
+
 } // hasSideEffects = 0
 }
 defm : LOCAL<I32>;
@@ -155,19 +180,26 @@ defm : LOCAL<F32>;
 defm : LOCAL<F64>;
 defm : LOCAL<V128>, Requires<[HasSIMD128]>;
 
+// Set TSFlags{0} to 1 to indicate that the variable_ops are immediates.
+// Set TSFlags{2} to 1 to indicate that the immediates are ValTypes.
+def DECLARE_LOCALS : I<(outs), (ins variable_ops), [], ".local  \t"> {
+  let TSFlags{0} = 1;
+  let TSFlags{2} = 1;
+}
+
 let isMoveImm = 1, isAsCheapAsAMove = 1, isReMaterializable = 1 in {
 def CONST_I32 : I<(outs I32:$res), (ins i32imm_op:$imm),
                   [(set I32:$res, imm:$imm)],
-                  "i32.const\t$res, $imm">;
+                  "i32.const\t$res, $imm", 0x10>;
 def CONST_I64 : I<(outs I64:$res), (ins i64imm_op:$imm),
                   [(set I64:$res, imm:$imm)],
-                  "i64.const\t$res, $imm">;
+                  "i64.const\t$res, $imm", 0x11>;
 def CONST_F32 : I<(outs F32:$res), (ins f32imm_op:$imm),
                   [(set F32:$res, fpimm:$imm)],
-                  "f32.const\t$res, $imm">;
+                  "f32.const\t$res, $imm", 0x13>;
 def CONST_F64 : I<(outs F64:$res), (ins f64imm_op:$imm),
                   [(set F64:$res, fpimm:$imm)],
-                  "f64.const\t$res, $imm">;
+                  "f64.const\t$res, $imm", 0x12>;
 } // isMoveImm = 1, isAsCheapAsAMove = 1, isReMaterializable = 1
 
 } // Defs = [ARGUMENTS]