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llvm-mirror/test/Transforms/LICM/hoist-alloc.ll
Philip Reames d5252f4ce6 [nofree] Restrict semantics to memory visible to caller 
This patch clarifies the semantics of the nofree function attribute to make clear that it provides an "as if" semantic. That is, a nofree function is guaranteed not to free memory which existed before the call, but might allocate and then deallocate that same memory within the lifetime of the callee.

This is the result of the discussion on llvm-dev under the thread "Ambiguity in the nofree function attribute".

The most important part of this change is the LangRef wording. The rest is minor comment changes to emphasize the new semantics where code was accidentally consistent, and fix one place which wasn't consistent. That one place is currently narrowly used as it is primarily part of the ongoing (and not yet enabled) deref-at-point semantics work.

Differential Revision: https://reviews.llvm.org/D100141
2021-04-16 11:38:55 -07:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -basic-aa -licm -use-dereferenceable-at-point-semantics=0 < %s | FileCheck %s
; RUN: opt -S -basic-aa -licm -use-dereferenceable-at-point-semantics=1 < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
declare void @unknown()
declare void @init(i8* nocapture)
declare void @use(i8)
define i8 @test_sink_alloca() {
; CHECK-LABEL: @test_sink_alloca(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A:%.*]] = alloca [32 x i8], align 1
; CHECK-NEXT: [[A_RAW:%.*]] = bitcast [32 x i8]* [[A]] to i8*
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[ADDR_LE:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: [[RES_LE:%.*]] = load i8, i8* [[ADDR_LE]], align 1
; CHECK-NEXT: ret i8 [[RES_LE]]
;
entry:
%a = alloca [32 x i8]
%a.raw = bitcast [32 x i8]* %a to i8*
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i8 %res
}
define i8 @test_hoist_alloca() {
; CHECK-LABEL: @test_hoist_alloca(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A:%.*]] = alloca [32 x i8], align 1
; CHECK-NEXT: [[A_RAW:%.*]] = bitcast [32 x i8]* [[A]] to i8*
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], [[FOR_BODY]] ]
; CHECK-NEXT: ret i8 [[RES_LCSSA]]
;
entry:
%a = alloca [32 x i8]
%a.raw = bitcast [32 x i8]* %a to i8*
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i8 %res
}
; The attributes listed here are a) inferred by -O3 from the names
; and b) required for a standalone test. We're very inconsistent about
; which decisions we drive from TLI vs assume attributes have been infered.
declare void @free(i8* nocapture)
declare noalias i8* @malloc(i64)
define i8 @test_sink_malloc() {
; CHECK-LABEL: @test_sink_malloc(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @malloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[ADDR_LE:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: [[RES_LE:%.*]] = load i8, i8* [[ADDR_LE]], align 1
; CHECK-NEXT: call void @free(i8* [[A_RAW]])
; CHECK-NEXT: ret i8 [[RES_LE]]
;
entry:
; Mark as nonnull to simplify test
%a.raw = call nonnull i8* @malloc(i64 32)
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
call void @free(i8* %a.raw)
ret i8 %res
}
; TODO: We can hoist the load in this case, but only once we have
; some form of context sensitive free analysis.
define i8 @test_hoist_malloc() {
; CHECK-LABEL: @test_hoist_malloc(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @malloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], [[FOR_BODY]] ]
; CHECK-NEXT: call void @free(i8* [[A_RAW]])
; CHECK-NEXT: ret i8 [[RES_LCSSA]]
;
entry:
%a.raw = call nonnull i8* @malloc(i64 32)
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
call void @free(i8* %a.raw)
ret i8 %res
}
define i8 @test_hoist_malloc_leak() nofree nosync {
; CHECK-LABEL: @test_hoist_malloc_leak(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @malloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], [[FOR_BODY]] ]
; CHECK-NEXT: ret i8 [[RES_LCSSA]]
;
entry:
%a.raw = call nonnull i8* @malloc(i64 32)
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i8 %res
}
; In this case, we can't hoist the load out of the loop as the memory it
; accesses may have been conditionally freed in a manner correlated with
; whether the load is reached in the loop.
define void @test_hoist_malloc_cond_free(i1 %c) {
; CHECK-LABEL: @test_hoist_malloc_cond_free(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @malloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: br i1 [[C:%.*]], label [[COND_FREE:%.*]], label [[PREHEADER:%.*]]
; CHECK: cond.free:
; CHECK-NEXT: call void @free(i8* [[A_RAW]])
; CHECK-NEXT: br label [[PREHEADER]]
; CHECK: preheader:
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ], [ 0, [[PREHEADER]] ]
; CHECK-NEXT: br i1 [[C]], label [[FOR_END:%.*]], label [[LOOP_LATCH]]
; CHECK: loop.latch:
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
%a.raw = call nonnull i8* @malloc(i64 32)
call void @init(i8* %a.raw)
br i1 %c, label %cond.free, label %preheader
cond.free:
call void @free(i8* %a.raw)
br label %preheader
preheader:
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %loop.latch ], [ 0, %preheader ]
br i1 %c, label %for.end, label %loop.latch
loop.latch:
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret void
}
define i8 @test_sink_malloc_cond_free(i1 %c) {
; CHECK-LABEL: @test_sink_malloc_cond_free(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @malloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: br i1 [[C:%.*]], label [[COND_FREE:%.*]], label [[PREHEADER:%.*]]
; CHECK: cond.free:
; CHECK-NEXT: call void @free(i8* [[A_RAW]])
; CHECK-NEXT: br label [[PREHEADER]]
; CHECK: preheader:
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ], [ 0, [[PREHEADER]] ]
; CHECK-NEXT: br i1 [[C]], label [[FOR_END_SPLIT_LOOP_EXIT1:%.*]], label [[LOOP_LATCH]]
; CHECK: loop.latch:
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END_SPLIT_LOOP_EXIT:%.*]], label [[FOR_BODY]]
; CHECK: for.end.split.loop.exit:
; CHECK-NEXT: [[ADDR_LE:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: [[RES_LE:%.*]] = load i8, i8* [[ADDR_LE]], align 1
; CHECK-NEXT: br label [[FOR_END:%.*]]
; CHECK: for.end.split.loop.exit1:
; CHECK-NEXT: [[PHI_PH2:%.*]] = phi i8 [ 0, [[FOR_BODY]] ]
; CHECK-NEXT: br label [[FOR_END]]
; CHECK: for.end:
; CHECK-NEXT: [[PHI:%.*]] = phi i8 [ [[RES_LE]], [[FOR_END_SPLIT_LOOP_EXIT]] ], [ [[PHI_PH2]], [[FOR_END_SPLIT_LOOP_EXIT1]] ]
; CHECK-NEXT: ret i8 [[PHI]]
;
entry:
%a.raw = call nonnull i8* @malloc(i64 32)
call void @init(i8* %a.raw)
br i1 %c, label %cond.free, label %preheader
cond.free:
call void @free(i8* %a.raw)
br label %preheader
preheader:
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %loop.latch ], [ 0, %preheader ]
br i1 %c, label %for.end, label %loop.latch
loop.latch:
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
%phi = phi i8 [%res, %loop.latch], [0, %for.body]
ret i8 %phi
}
declare noalias i8* @my_alloc(i64) allocsize(0)
; We would need context sensitive reasoning about frees (which we don't
; don't currently have) to hoist the load in this example.
define i8 @test_hoist_allocsize() {
; CHECK-LABEL: @test_hoist_allocsize(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @my_alloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], [[FOR_BODY]] ]
; CHECK-NEXT: call void @free(i8* [[A_RAW]])
; CHECK-NEXT: ret i8 [[RES_LCSSA]]
;
entry:
%a.raw = call nonnull i8* @my_alloc(i64 32)
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
call void @free(i8* %a.raw)
ret i8 %res
}
define i8 @test_hoist_allocsize_leak() nofree nosync {
; CHECK-LABEL: @test_hoist_allocsize_leak(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[A_RAW:%.*]] = call nonnull i8* @my_alloc(i64 32)
; CHECK-NEXT: call void @init(i8* [[A_RAW]])
; CHECK-NEXT: [[ADDR:%.*]] = getelementptr i8, i8* [[A_RAW]], i32 31
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @unknown()
; CHECK-NEXT: [[RES:%.*]] = load i8, i8* [[ADDR]], align 1
; CHECK-NEXT: call void @use(i8 [[RES]])
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[IV_NEXT]], 200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
; CHECK: for.end:
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi i8 [ [[RES]], [[FOR_BODY]] ]
; CHECK-NEXT: ret i8 [[RES_LCSSA]]
;
entry:
%a.raw = call nonnull i8* @my_alloc(i64 32)
call void @init(i8* %a.raw)
br label %for.body
for.body:
%iv = phi i64 [ %iv.next, %for.body ], [ 0, %entry ]
call void @unknown() ;; may throw
%addr = getelementptr i8, i8* %a.raw, i32 31
%res = load i8, i8* %addr
call void @use(i8 %res)
%iv.next = add nuw nsw i64 %iv, 1
%exitcond = icmp eq i64 %iv.next, 200
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i8 %res
}
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