commit bc536c710150f53b5ae5cd6b7693636e77992d0a
Author: Dawid Jurczak <dawid_jurek@vp.pl>
Date:   Fri Jul 23 11:51:59 2021 +0200

    Revert "[DSE] Transform memset + malloc --> calloc (PR25892)"
    
    This reverts commit 43234b1595125ba2b5c23e7b28f5a67041c77673.
    
    Reason: We should detect that we are implementing 'calloc' and bail out.

diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index a631fbe93673..d22b3f409585 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -56,7 +56,6 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
@@ -79,7 +78,6 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
-#include "llvm/Transforms/Utils/BuildLibCalls.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <algorithm>
 #include <cassert>
@@ -507,12 +505,7 @@ memoryIsNotModifiedBetween(Instruction *FirstI, Instruction *SecondI,
   BasicBlock::iterator SecondBBI(SecondI);
   BasicBlock *FirstBB = FirstI->getParent();
   BasicBlock *SecondBB = SecondI->getParent();
-  MemoryLocation MemLoc;
-  if (auto *MemSet = dyn_cast<MemSetInst>(SecondI))
-    MemLoc = MemoryLocation::getForDest(MemSet);
-  else
-    MemLoc = MemoryLocation::get(SecondI);
-
+  MemoryLocation MemLoc = MemoryLocation::get(SecondI);
   auto *MemLocPtr = const_cast<Value *>(MemLoc.Ptr);
 
   // Start checking the SecondBB.
@@ -826,17 +819,14 @@ bool isNoopIntrinsic(Instruction *I) {
 }
 
 // Check if we can ignore \p D for DSE.
-bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller,
-                const TargetLibraryInfo &TLI) {
+bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller) {
   Instruction *DI = D->getMemoryInst();
   // Calls that only access inaccessible memory cannot read or write any memory
   // locations we consider for elimination.
   if (auto *CB = dyn_cast<CallBase>(DI))
-    if (CB->onlyAccessesInaccessibleMemory()) {
-      if (isAllocLikeFn(DI, &TLI))
-        return false;
+    if (CB->onlyAccessesInaccessibleMemory())
       return true;
-    }
+
   // We can eliminate stores to locations not visible to the caller across
   // throwing instructions.
   if (DI->mayThrow() && !DefVisibleToCaller)
@@ -851,7 +841,7 @@ bool canSkipDef(MemoryDef *D, bool DefVisibleToCaller,
     return true;
 
   // Skip intrinsics that do not really read or modify memory.
-  if (isNoopIntrinsic(DI))
+  if (isNoopIntrinsic(D->getMemoryInst()))
     return true;
 
   return false;
@@ -1399,7 +1389,7 @@ struct DSEState {
       MemoryDef *CurrentDef = cast<MemoryDef>(Current);
       Instruction *CurrentI = CurrentDef->getMemoryInst();
 
-      if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(DefUO), TLI))
+      if (canSkipDef(CurrentDef, !isInvisibleToCallerBeforeRet(DefUO)))
         continue;
 
       // Before we try to remove anything, check for any extra throwing
@@ -1826,55 +1816,13 @@ struct DSEState {
 
     if (StoredConstant && StoredConstant->isNullValue()) {
       auto *DefUOInst = dyn_cast<Instruction>(DefUO);
-      if (DefUOInst) {
-        if (isCallocLikeFn(DefUOInst, &TLI)) {
-          auto *UnderlyingDef =
-              cast<MemoryDef>(MSSA.getMemoryAccess(DefUOInst));
-          // If UnderlyingDef is the clobbering access of Def, no instructions
-          // between them can modify the memory location.
-          auto *ClobberDef =
-              MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def);
-          return UnderlyingDef == ClobberDef;
-        }
-
-        if (MemSet) {
-          if (F.hasFnAttribute(Attribute::SanitizeMemory))
-            return false;
-          auto *Malloc = const_cast<CallInst *>(dyn_cast<CallInst>(DefUOInst));
-          if (!Malloc)
-            return false;
-          auto *InnerCallee = Malloc->getCalledFunction();
-          if (!InnerCallee)
-            return false;
-          LibFunc Func;
-          if (!TLI.getLibFunc(*InnerCallee, Func) || !TLI.has(Func) ||
-              Func != LibFunc_malloc)
-            return false;
-          if (Malloc->getOperand(0) == MemSet->getLength()) {
-            if (DT.dominates(Malloc, MemSet) &&
-                memoryIsNotModifiedBetween(Malloc, MemSet, BatchAA, DL, &DT)) {
-              IRBuilder<> IRB(Malloc);
-              const auto &DL = Malloc->getModule()->getDataLayout();
-              AttributeList EmptyList;
-              if (auto *Calloc = emitCalloc(
-                      ConstantInt::get(IRB.getIntPtrTy(DL), 1),
-                      Malloc->getArgOperand(0), EmptyList, IRB, TLI)) {
-                MemorySSAUpdater Updater(&MSSA);
-                auto *LastDef = cast<MemoryDef>(
-                    Updater.getMemorySSA()->getMemoryAccess(Malloc));
-                auto *NewAccess = Updater.createMemoryAccessAfter(
-                    cast<Instruction>(Calloc), LastDef, LastDef);
-                auto *NewAccessMD = cast<MemoryDef>(NewAccess);
-                Updater.insertDef(NewAccessMD, /*RenameUses=*/true);
-                Updater.removeMemoryAccess(Malloc);
-                Malloc->replaceAllUsesWith(Calloc);
-                Malloc->eraseFromParent();
-                return true;
-              }
-              return false;
-            }
-          }
-        }
+      if (DefUOInst && isCallocLikeFn(DefUOInst, &TLI)) {
+        auto *UnderlyingDef = cast<MemoryDef>(MSSA.getMemoryAccess(DefUOInst));
+        // If UnderlyingDef is the clobbering access of Def, no instructions
+        // between them can modify the memory location.
+        auto *ClobberDef =
+            MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def);
+        return UnderlyingDef == ClobberDef;
       }
     }
 
diff --git a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
index 083ecc2b4a1a..184653982a6a 100644
--- a/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
+++ b/llvm/test/Transforms/DeadStoreElimination/noop-stores.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -basic-aa -dse -S | FileCheck %s
-; RUN: opt < %s -aa-pipeline=basic-aa -passes='dse,verify<memoryssa>' -S | FileCheck %s
+; RUN: opt < %s -aa-pipeline=basic-aa -passes=dse -S | FileCheck %s
 target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
 
 declare i8* @calloc(i64, i64)
@@ -309,128 +309,6 @@ entry:
   ret void
 }
 
-declare noalias i8* @malloc(i64)
-declare noalias i8* @_Znwm(i64)
-declare void @clobber_memory(float*)
-
-; based on pr25892_lite
-define i8* @zero_memset_after_malloc(i64 %size) {
-; CHECK-LABEL: @zero_memset_after_malloc(
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]])
-; CHECK-NEXT:    ret i8* [[CALL]]
-;
-  %call = call i8* @malloc(i64 %size) inaccessiblememonly
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false)
-  ret i8* %call
-}
-
-; based on pr25892_lite
-define i8* @zero_memset_after_malloc_with_intermediate_clobbering(i64 %size) {
-; CHECK-LABEL: @zero_memset_after_malloc_with_intermediate_clobbering(
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @malloc(i64 [[SIZE:%.*]])
-; CHECK-NEXT:    [[BC:%.*]] = bitcast i8* [[CALL]] to float*
-; CHECK-NEXT:    call void @clobber_memory(float* [[BC]])
-; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE]], i1 false)
-; CHECK-NEXT:    ret i8* [[CALL]]
-;
-  %call = call i8* @malloc(i64 %size) inaccessiblememonly
-  %bc = bitcast i8* %call to float*
-  call void @clobber_memory(float* %bc)
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false)
-  ret i8* %call
-}
-
-; based on pr25892_lite
-define i8* @zero_memset_after_malloc_with_different_sizes(i64 %size) {
-; CHECK-LABEL: @zero_memset_after_malloc_with_different_sizes(
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @malloc(i64 [[SIZE:%.*]])
-; CHECK-NEXT:    [[SIZE2:%.*]] = add nsw i64 [[SIZE]], -1
-; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE2]], i1 false)
-; CHECK-NEXT:    ret i8* [[CALL]]
-;
-  %call = call i8* @malloc(i64 %size) inaccessiblememonly
-  %size2 = add nsw i64 %size, -1
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size2, i1 false)
-  ret i8* %call
-}
-
-; based on pr25892_lite
-define i8* @zero_memset_after_new(i64 %size) {
-; CHECK-LABEL: @zero_memset_after_new(
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @_Znwm(i64 [[SIZE:%.*]])
-; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* [[CALL]], i8 0, i64 [[SIZE]], i1 false)
-; CHECK-NEXT:    ret i8* [[CALL]]
-;
-  %call = call i8* @_Znwm(i64 %size)
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false)
-  ret i8* %call
-}
-
-; This should not create a calloc and should not crash the compiler.
-define i8* @notmalloc_memset(i64 %size, i8*(i64)* %notmalloc) {
-; CHECK-LABEL: @notmalloc_memset(
-; CHECK-NEXT:    [[CALL1:%.*]] = call i8* [[NOTMALLOC:%.*]](i64 [[SIZE:%.*]])
-; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* [[CALL1]], i8 0, i64 [[SIZE]], i1 false)
-; CHECK-NEXT:    ret i8* [[CALL1]]
-;
-  %call1 = call i8* %notmalloc(i64 %size)
-  call void @llvm.memset.p0i8.i64(i8* %call1, i8 0, i64 %size, i1 false)
-  ret i8* %call1
-}
-
-define float* @pr25892(i64 %size) {
-; CHECK-LABEL: @pr25892(
-; CHECK:       entry:
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]])
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[CALL]], null
-; CHECK-NEXT:    br i1 [[CMP]], label [[CLEANUP:%.*]], label [[IF_END:%.*]]
-; CHECK:       if.end:
-; CHECK-NEXT:    [[BC:%.*]] = bitcast i8* [[CALL]] to float*
-; CHECK-NEXT:    br label [[CLEANUP]]
-; CHECK:       cleanup:
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi float* [ [[BC]], [[IF_END]] ], [ null, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    ret float* [[RETVAL_0]]
-;
-entry:
-  %call = call i8* @malloc(i64 %size) inaccessiblememonly
-  %cmp = icmp eq i8* %call, null
-  br i1 %cmp, label %cleanup, label %if.end
-if.end:
-  %bc = bitcast i8* %call to float*
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false)
-  br label %cleanup
-cleanup:
-  %retval.0 = phi float* [ %bc, %if.end ], [ null, %entry ]
-  ret float* %retval.0
-}
-
-; CHECK-LABEL: @pr25892_with_extra_store(
-; CHECK:       entry:
-; CHECK-NEXT:    [[CALL:%.*]] = call i8* @calloc(i64 1, i64 [[SIZE:%.*]])
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[CALL]], null
-; CHECK-NEXT:    br i1 [[CMP]], label [[CLEANUP:%.*]], label [[IF_END:%.*]]
-; CHECK:       if.end:
-; CHECK-NEXT:    [[BC:%.*]] = bitcast i8* [[CALL]] to float*
-; CHECK-NEXT:    br label [[CLEANUP]]
-; CHECK:       cleanup:
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi float* [ [[BC]], [[IF_END]] ], [ null, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    ret float* [[RETVAL_0]]
-;
-define float* @pr25892_with_extra_store(i64 %size) {
-entry:
-  %call = call i8* @malloc(i64 %size) inaccessiblememonly
-  %cmp = icmp eq i8* %call, null
-  br i1 %cmp, label %cleanup, label %if.end
-if.end:
-  %bc = bitcast i8* %call to float*
-  call void @llvm.memset.p0i8.i64(i8* %call, i8 0, i64 %size, i1 false)
-  store i8 0, i8* %call, align 1
-  br label %cleanup
-cleanup:
-  %retval.0 = phi float* [ %bc, %if.end ], [ null, %entry ]
-  ret float* %retval.0
-}
-
 ; PR50143
 define i8* @store_zero_after_calloc_inaccessiblememonly() {
 ; CHECK-LABEL: @store_zero_after_calloc_inaccessiblememonly(