[llvm] 89c5647 - [DSE] Handle unexpected memory attribute on malloc (PR64827)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-08-28T15:06:53+02:00
New Revision: 89c564704e8034729088eb4be3b90ffe958bd079

URL: https://github.com/llvm/llvm-project/commit/89c564704e8034729088eb4be3b90ffe958bd079
DIFF: https://github.com/llvm/llvm-project/commit/89c564704e8034729088eb4be3b90ffe958bd079.diff

LOG: [DSE] Handle unexpected memory attribute on malloc (PR64827)

Make sure we don't crash if we encounter a malloc with memory(none).

Related to https://github.com/llvm/llvm-project/issues/64827.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    llvm/test/Transforms/DeadStoreElimination/noop-stores.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 6fd3f5ce753ce8..b6f9cb6cd2d0bb 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1861,6 +1861,10 @@ struct DSEState {
     if (!TLI.getLibFunc(*InnerCallee, Func) || !TLI.has(Func) ||
         Func != LibFunc_malloc)
       return false;
+    // Gracefully handle malloc with unexpected memory attributes.
+    auto *MallocDef = dyn_cast_or_null<MemoryDef>(MSSA.getMemoryAccess(Malloc));
+    if (!MallocDef)
+      return false;
 
     auto shouldCreateCalloc = [](CallInst *Malloc, CallInst *Memset) {
       // Check for br(icmp ptr, null), truebb, falsebb) pattern at the end
@@ -1894,11 +1898,9 @@ struct DSEState {
     if (!Calloc)
       return false;
     MemorySSAUpdater Updater(&MSSA);
-    auto *LastDef =
-      cast<MemoryDef>(Updater.getMemorySSA()->getMemoryAccess(Malloc));
     auto *NewAccess =
       Updater.createMemoryAccessAfter(cast<Instruction>(Calloc), nullptr,
-                                      LastDef);
+                                      MallocDef);
     auto *NewAccessMD = cast<MemoryDef>(NewAccess);
     Updater.insertDef(NewAccessMD, /*RenameUses=*/true);
     Updater.removeMemoryAccess(Malloc);

diff  --git a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
index 8790bf640ca1a1..3703b8d039ead0 100644
--- a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
@@ -667,6 +667,17 @@ if.end:
   ret ptr %3
 }
 
+define ptr @readnone_malloc() {
+; CHECK-LABEL: @readnone_malloc(
+; CHECK-NEXT:    [[ALLOC:%.*]] = call ptr @malloc(i64 16) #[[ATTR8:[0-9]+]]
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr [[ALLOC]], i8 0, i64 16, i1 false)
+; CHECK-NEXT:    ret ptr [[ALLOC]]
+;
+  %alloc = call ptr @malloc(i64 16) memory(none)
+  call void @llvm.memset.p0.i64(ptr %alloc, i8 0, i64 16, i1 false)
+  ret ptr %alloc
+}
+
 define void @store_same_i32_to_mayalias_loc(ptr %q, ptr %p) {
 ; CHECK-LABEL: @store_same_i32_to_mayalias_loc(
 ; CHECK-NEXT:    [[V:%.*]] = load i32, ptr [[P:%.*]], align 4