[WebAssembly] Guard use of getSymbolName with isSymbol

[dschuff]

WebAssemblyRegStackfy checks for writes to the stack pointer to avoid
stackifying across them, but it wasn't prepared for other global_set
instructions (such as writes in addrspace 1).

Fixes #156055

[llvmbot]

@llvm/pr-subscribers-backend-webassembly

Author: Derek Schuff (dschuff)

Changes

WebAssemblyRegStackfy checks for writes to the stack pointer to avoid
stackifying across them, but it wasn't prepared for other global_set
instructions (such as writes in addrspace 1).

Fixes #156055

---

Full diff: https://github.com/llvm/llvm-project/pull/156105.diff

2 Files Affected:

• (modified) llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp (+2-1)
• (modified) llvm/test/CodeGen/WebAssembly/global-set.ll (+15)

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
index bc91c6424b63e..08ca20b5eef6e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -247,7 +247,8 @@ static void query(const MachineInstr &MI, bool &Read, bool &Write,
   // Check for writes to __stack_pointer global.
   if ((MI.getOpcode() == WebAssembly::GLOBAL_SET_I32 ||
        MI.getOpcode() == WebAssembly::GLOBAL_SET_I64) &&
-      strcmp(MI.getOperand(0).getSymbolName(), "__stack_pointer") == 0)
+      MI.getOperand(0).isSymbol() &&
+      !strcmp(MI.getOperand(0).getSymbolName(), "__stack_pointer"))
     StackPointer = true;
 
   // Analyze calls.
diff --git a/llvm/test/CodeGen/WebAssembly/global-set.ll b/llvm/test/CodeGen/WebAssembly/global-set.ll
index 7db374528fe9b..f76006c2863b2 100644
--- a/llvm/test/CodeGen/WebAssembly/global-set.ll
+++ b/llvm/test/CodeGen/WebAssembly/global-set.ll
@@ -45,6 +45,21 @@ define void @set_f64_global(double %v) {
   ret void
 }
 
+declare i32 @get_i32()
+define i32 @testFunc() {
+; CHECK-LABEL: testFunc:
+; CHECK-NEXT: .functype
+; CHECK-NEXT: .local
+; CHECK-NEXT: call get_i32
+; CHECK-NEXT: local.tee
+; CHECK-NEXT: global.set i32_global
+; CHECK-NEXT: local.get
+; CHECK-NEXT: end_function
+  %1 = call i32 @get_i32()
+  store i32 %1, ptr addrspace(1) @i32_global
+  ret i32 %1
+}
+
 ; CHECK: .globaltype i32_global, i32
 ; CHECK: .globl i32_global
 ; CHECK-LABEL: i32_global:

[aheejin]

LGTM % the test comment

[aheejin]

Without %2 = add i32 %1, 1 in the reproducer in #156055, this doesn't seem to trigger the assertion