[WebAssembly] Fix ADJCALLSTACKDOWN/UP use/defs

Summary:
ADJCALLSTACK{DOWN,UP} (aka CALLSEQ_{START,END}) MIs are supposed to use
and def the stack pointer. Since they do not, all the nodes are being
eliminated by DeadMachineInstructionElim, so they aren't in the IR when
PrologEpilogInserter/eliminateCallFramePseudo needs them.

This change fixes that, but since RegStackify will not stackify across
them (and it runs early, before PEI), change LowerCall to only emit them
when the call frame size is > 0. That makes the current code work the
same way and makes code handled by D15344 also work the same way. We can
expand the condition beyond NumBytes > 0 in the future if needed.

Reviewers: sunfish, jfb

Subscribers: jfb, dschuff, llvm-commits

Differential Revision: http://reviews.llvm.org/D15459

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255356 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 4ef0846d311a2a0f31e2984747b5ddc460d9a155..76df63b54074bce38f86734ebaf2e1ca12c3f08d 100644 (file)
--- a/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -359,8 +359,11 @@ WebAssemblyTargetLowering::LowerCall(CallLoweringInfo &CLI,
 
   unsigned NumBytes = CCInfo.getAlignedCallFrameSize();
 
-  auto NB = DAG.getConstant(NumBytes, DL, PtrVT, true);
-  Chain = DAG.getCALLSEQ_START(Chain, NB, DL);
+  SDValue NB;
+  if (NumBytes) {
+    NB = DAG.getConstant(NumBytes, DL, PtrVT, true);
+    Chain = DAG.getCALLSEQ_START(Chain, NB, DL);
+  }
 
   if (IsVarArg) {
     // For non-fixed arguments, next emit stores to store the argument values
@@ -420,8 +423,10 @@ WebAssemblyTargetLowering::LowerCall(CallLoweringInfo &CLI,
     Chain = Res.getValue(1);
   }
 
-  SDValue Unused = DAG.getUNDEF(PtrVT);
-  Chain = DAG.getCALLSEQ_END(Chain, NB, Unused, SDValue(), DL);
+  if (NumBytes) {
+    SDValue Unused = DAG.getUNDEF(PtrVT);
+    Chain = DAG.getCALLSEQ_END(Chain, NB, Unused, SDValue(), DL);
+  }
 
   return Chain;
 }

diff --git a/lib/Target/WebAssembly/WebAssemblyInstrCall.td b/lib/Target/WebAssembly/WebAssemblyInstrCall.td
index 0587c0b6613ed17d16b31cd457d7c664dae07052..6ea8cec73974e3f491b382a9858b043475e2aed8 100644 (file)
--- a/lib/Target/WebAssembly/WebAssemblyInstrCall.td
+++ b/lib/Target/WebAssembly/WebAssemblyInstrCall.td
@@ -18,7 +18,7 @@ let Defs = [ARGUMENTS] in {
 
 // Call sequence markers. These have an immediate which represents the amount of
 // stack space to allocate or free, which is used for varargs lowering.
-let isCodeGenOnly = 1 in {
+let Uses = [SP32, SP64], Defs = [SP32, SP64], isCodeGenOnly = 1 in {
 def ADJCALLSTACKDOWN : I<(outs), (ins i32imm:$amt),
                          [(WebAssemblycallseq_start timm:$amt)]>;
 def ADJCALLSTACKUP : I<(outs), (ins i32imm:$amt),