[Attributor] Enable heap-to-stack of any size

Enable Attributor's heap-to-stack to lower unbounded allocations given a max size of -1

Differential Revision: https://reviews.llvm.org/D97873

Author: wsmoses

llvm/lib/Transforms/IPO/AttributorAttributes.cpp

@@ -5166,13 +5166,25 @@ ChangeStatus AAHeapToStackImpl::updateImpl(Attributor &A) {
     }
 
     if (IsMalloc) {
+      if (MaxHeapToStackSize == -1) {
+        if (UsesCheck(I) || FreeCheck(I)) {
+          MallocCalls.insert(&I);
+          return true;
+        }
+      }
       if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(0)))
         if (Size->getValue().ule(MaxHeapToStackSize))
           if (UsesCheck(I) || FreeCheck(I)) {
             MallocCalls.insert(&I);
             return true;
           }
     } else if (IsAlignedAllocLike && isa<ConstantInt>(I.getOperand(0))) {
+      if (MaxHeapToStackSize == -1) {
+        if (UsesCheck(I) || FreeCheck(I)) {
+          MallocCalls.insert(&I);
+          return true;
+        }
+      }
       // Only if the alignment and sizes are constant.
       if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(1)))
         if (Size->getValue().ule(MaxHeapToStackSize))
@@ -5181,6 +5193,12 @@ ChangeStatus AAHeapToStackImpl::updateImpl(Attributor &A) {
             return true;
           }
     } else if (IsCalloc) {
+      if (MaxHeapToStackSize == -1) {
+        if (UsesCheck(I) || FreeCheck(I)) {
+          MallocCalls.insert(&I);
+          return true;
+        }
+      }
       bool Overflow = false;
       if (auto *Num = dyn_cast<ConstantInt>(I.getOperand(0)))
         if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(1)))

llvm/test/Transforms/Attributor/lowerheap.ll

@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --check-attributes
+; RUN: opt -max-heap-to-stack-size=-1 -attributor -enable-new-pm=0 -attributor-manifest-internal  -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=1 -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_CGSCC_NPM,NOT_CGSCC_OPM,NOT_TUNIT_NPM,IS__TUNIT____,IS________OPM,IS__TUNIT_OPM
+; RUN: opt -max-heap-to-stack-size=-1 -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal  -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=1 -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_CGSCC_OPM,NOT_CGSCC_NPM,NOT_TUNIT_OPM,IS__TUNIT____,IS________NPM,IS__TUNIT_NPM
+; RUN: opt -max-heap-to-stack-size=-1 -attributor-cgscc -enable-new-pm=0 -attributor-manifest-internal  -attributor-annotate-decl-cs -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_TUNIT_NPM,NOT_TUNIT_OPM,NOT_CGSCC_NPM,IS__CGSCC____,IS________OPM,IS__CGSCC_OPM
+; RUN: opt -max-heap-to-stack-size=-1 -aa-pipeline=basic-aa -passes=attributor-cgscc -attributor-manifest-internal  -attributor-annotate-decl-cs -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_TUNIT_NPM,NOT_TUNIT_OPM,NOT_CGSCC_OPM,IS__CGSCC____,IS________NPM,IS__CGSCC_NPM
+
+declare i64 @subfn(i8*) #0
+
+declare noalias i8* @malloc(i64)
+declare void @free(i8*)
+
+define i64 @f(i64 %len) {
+; IS________OPM-LABEL: define {{[^@]+}}@f
+; IS________OPM-SAME: (i64 [[LEN:%.*]]) {
+; IS________OPM-NEXT:  entry:
+; IS________OPM-NEXT:    [[MEM:%.*]] = call noalias i8* @malloc(i64 [[LEN]])
+; IS________OPM-NEXT:    [[RES:%.*]] = call i64 @subfn(i8* [[MEM]]) [[ATTR1:#.*]]
+; IS________OPM-NEXT:    call void @free(i8* [[MEM]])
+; IS________OPM-NEXT:    ret i64 [[RES]]
+;
+; IS________NPM-LABEL: define {{[^@]+}}@f
+; IS________NPM-SAME: (i64 [[LEN:%.*]]) {
+; IS________NPM-NEXT:  entry:
+; IS________NPM-NEXT:    [[TMP0:%.*]] = alloca i8, i64 [[LEN]], align 1
+; IS________NPM-NEXT:    [[RES:%.*]] = call i64 @subfn(i8* [[TMP0]]) [[ATTR1:#.*]]
+; IS________NPM-NEXT:    ret i64 [[RES]]
+;
+entry:
+  %mem = call i8* @malloc(i64 %len)
+  %res = call i64 @subfn(i8* %mem)
+  call void @free(i8* %mem)
+  ret i64 %res
+}
+
+attributes #0 = { nounwind willreturn }