[PATCH] D74875: [WebAssembly] Fix memory bug introduced in 52861809994c

[Thomas Lively via Phabricator via llvm-commits]

tlively created this revision.
tlively added a reviewer: aheejin.
Herald added subscribers: llvm-commits, sunfish, hiraditya, jgravelle-google, sbc100, dschuff.
Herald added a project: LLVM.

The instruction at `DefI` can sometimes be destroyed by
`rematerializeCheapDef`, so it should not be used after calling that
function. The fix is to use `Insert` instead when examining additional
multivalue stackifications. `Insert` is the address of the new
defining instruction after all moves and rematerializations have taken
place.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74875

Files:
  llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp


Index: llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -923,9 +923,9 @@
         // Stackifying a multivalue def may unlock in-place stackification of
         // subsequent defs. TODO: Handle the case where the consecutive uses are
         // not all in the same instruction.
-        auto *SubsequentDef = DefI->defs().begin();
+        auto *SubsequentDef = Insert->defs().begin();
         auto *SubsequentUse = &Use;
-        while (SubsequentDef != DefI->defs().end() &&
+        while (SubsequentDef != Insert->defs().end() &&
                SubsequentUse != Use.getParent()->uses().end()) {
           if (!SubsequentDef->isReg() || !SubsequentUse->isReg())
             break;


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