https://github.com/tru updated https://github.com/llvm/llvm-project/pull/150187
>From dbe3ba076758b1f489b4c37cd03a69e320a5019f Mon Sep 17 00:00:00 2001
From: Heejin Ahn <ahee...@gmail.com>
Date: Tue, 22 Jul 2025 15:34:23 -0700
Subject: [PATCH] [WebAssembly] Unstackify registers with no uses in
ExplicitLocals (#149626)
There are cases we end up removing some intructions that use stackified
registers after RegStackify. For example,
```wasm
bb.0:
%0 = ... ;; %0 is stackified
br_if %bb.1, %0
bb.1:
```
In this code, br_if will be removed in CFGSort, so we should unstackify
%0 so that it can be correctly dropped in ExplicitLocals.
Rather than handling this in case-by-case basis, this PR just
unstackifies all stackifies register with no uses in the beginning of
ExplicitLocals, so that they can be correctly dropped.
Fixes #149097.
(cherry picked from commit b13bca7387a7aad6eaf3fa1c55bd06fe091f65ed)
---
.../WebAssembly/WebAssemblyExplicitLocals.cpp | 12 +++++++--
.../CodeGen/WebAssembly/removed-terminator.ll | 26 +++++++++++++++++++
2 files changed, 36 insertions(+), 2 deletions(-)
create mode 100644 llvm/test/CodeGen/WebAssembly/removed-terminator.ll
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
index 2662241ef8499..e6486e247209b 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
@@ -256,9 +256,17 @@ bool
WebAssemblyExplicitLocals::runOnMachineFunction(MachineFunction &MF) {
// Precompute the set of registers that are unused, so that we can insert
// drops to their defs.
+ // And unstackify any stackified registers that don't have any uses, so that
+ // they can be dropped later. This can happen when transformations after
+ // RegStackify remove instructions using stackified registers.
BitVector UseEmpty(MRI.getNumVirtRegs());
- for (unsigned I = 0, E = MRI.getNumVirtRegs(); I < E; ++I)
- UseEmpty[I] = MRI.use_empty(Register::index2VirtReg(I));
+ for (unsigned I = 0, E = MRI.getNumVirtRegs(); I < E; ++I) {
+ Register Reg = Register::index2VirtReg(I);
+ if (MRI.use_empty(Reg)) {
+ UseEmpty[I] = true;
+ MFI.unstackifyVReg(Reg);
+ }
+ }
// Visit each instruction in the function.
for (MachineBasicBlock &MBB : MF) {
diff --git a/llvm/test/CodeGen/WebAssembly/removed-terminator.ll
b/llvm/test/CodeGen/WebAssembly/removed-terminator.ll
new file mode 100644
index 0000000000000..188f6f67eee8b
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/removed-terminator.ll
@@ -0,0 +1,26 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
UTC_ARGS: --version 5
+; RUN: llc -O0 -verify-machineinstrs < %s | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+define void @test(i1 %x) {
+; CHECK-LABEL: test:
+; CHECK: .functype test (i32) -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: local.get 0
+; CHECK-NEXT: i32.const -1
+; CHECK-NEXT: i32.xor
+; CHECK-NEXT: i32.const 1
+; CHECK-NEXT: i32.and
+; CHECK-NEXT: drop
+; CHECK-NEXT: # %bb.1: # %exit
+; CHECK-NEXT: return
+ %y = xor i1 %x, true
+ ; This br_if's operand (%y) is stackified in RegStackify. But this terminator
+ ; will be removed in CFGSort after that. We need to make sure we unstackify
%y
+ ; so that it can be dropped in ExplicitLocals.
+ br i1 %y, label %exit, label %exit
+
+exit:
+ ret void
+}
_______________________________________________
llvm-branch-commits mailing list
llvm-branch-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
