forked from OSchip/llvm-project
165 lines
5.0 KiB
LLVM
165 lines
5.0 KiB
LLVM
; RUN: opt -instcombine -S < %s | FileCheck %s
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@gp = global i32* null, align 8
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declare i8* @malloc(i64) #1
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define i1 @compare_global_trivialeq() {
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%m = call i8* @malloc(i64 4)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8
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%cmp = icmp eq i32* %bc, %lgp
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ret i1 %cmp
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; CHECK-LABEL: compare_global_trivialeq
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; CHECK: ret i1 false
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}
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define i1 @compare_global_trivialne() {
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%m = call i8* @malloc(i64 4)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8
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%cmp = icmp ne i32* %bc, %lgp
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ret i1 %cmp
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; CHECK-LABEL: compare_global_trivialne
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; CHECK: ret i1 true
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}
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; Although the %m is marked nocapture in the deopt operand in call to function f,
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; we cannot remove the alloc site: call to malloc
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; The comparison should fold to false irrespective of whether the call to malloc can be elided or not
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declare void @f()
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define i1 @compare_and_call_with_deopt() {
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; CHECK-LABEL: compare_and_call_with_deopt
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%m = call i8* @malloc(i64 24)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8, !nonnull !0
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%cmp = icmp eq i32* %lgp, %bc
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tail call void @f() [ "deopt"(i8* %m) ]
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ret i1 %cmp
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; CHECK: ret i1 false
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}
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; Same functon as above with deopt operand in function f, but comparison is NE
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define i1 @compare_ne_and_call_with_deopt() {
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; CHECK-LABEL: compare_ne_and_call_with_deopt
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%m = call i8* @malloc(i64 24)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8, !nonnull !0
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%cmp = icmp ne i32* %lgp, %bc
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tail call void @f() [ "deopt"(i8* %m) ]
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ret i1 %cmp
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; CHECK: ret i1 true
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}
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; Same function as above, but global not marked nonnull, and we cannot fold the comparison
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define i1 @compare_ne_global_maybe_null() {
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; CHECK-LABEL: compare_ne_global_maybe_null
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%m = call i8* @malloc(i64 24)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp
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%cmp = icmp ne i32* %lgp, %bc
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tail call void @f() [ "deopt"(i8* %m) ]
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ret i1 %cmp
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; CHECK: ret i1 %cmp
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}
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; FIXME: The comparison should fold to false since %m escapes (call to function escape)
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; after the comparison.
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declare void @escape(i8*)
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define i1 @compare_and_call_after() {
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; CHECK-LABEL: compare_and_call_after
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%m = call i8* @malloc(i64 24)
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8, !nonnull !0
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%cmp = icmp eq i32* %bc, %lgp
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br i1 %cmp, label %escape_call, label %just_return
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escape_call:
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call void @escape(i8* %m)
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ret i1 true
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just_return:
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ret i1 %cmp
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}
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define i1 @compare_distinct_mallocs() {
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%m = call i8* @malloc(i64 4)
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%n = call i8* @malloc(i64 4)
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%cmp = icmp eq i8* %m, %n
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ret i1 %cmp
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; CHECK-LABEL: compare_distinct_mallocs
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; CHECK: ret i1 false
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}
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; the compare is folded to true since the folding compare looks through bitcasts.
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; call to malloc and the bitcast instructions are elided after that since there are no uses of the malloc
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define i1 @compare_samepointer_under_bitcast() {
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%m = call i8* @malloc(i64 4)
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%bc = bitcast i8* %m to i32*
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%bcback = bitcast i32* %bc to i8*
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%cmp = icmp eq i8* %m, %bcback
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ret i1 %cmp
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; CHECK-LABEL: compare_samepointer_under_bitcast
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; CHECK: ret i1 true
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}
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; the compare is folded to true since the folding compare looks through bitcasts.
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; The malloc call for %m cannot be elided since it is used in the call to function f.
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define i1 @compare_samepointer_escaped() {
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%m = call i8* @malloc(i64 4)
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%bc = bitcast i8* %m to i32*
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%bcback = bitcast i32* %bc to i8*
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%cmp = icmp eq i8* %m, %bcback
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call void @f() [ "deopt"(i8* %m) ]
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ret i1 %cmp
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; CHECK-LABEL: compare_samepointer_escaped
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; CHECK-NEXT: %m = call i8* @malloc(i64 4)
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; CHECK-NEXT: call void @f() [ "deopt"(i8* %m) ]
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; CHECK: ret i1 true
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}
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; Technically, we can fold the %cmp2 comparison, even though %m escapes through
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; the ret statement since `ret` terminates the function and we cannot reach from
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; the ret to cmp.
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; FIXME: Folding this %cmp2 when %m escapes through ret could be an issue with
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; cross-threading data dependencies since we do not make the distinction between
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; atomic and non-atomic loads in capture tracking.
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define i8* @compare_ret_escape(i8* %c) {
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%m = call i8* @malloc(i64 4)
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%n = call i8* @malloc(i64 4)
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%cmp = icmp eq i8* %n, %c
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br i1 %cmp, label %retst, label %chk
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retst:
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ret i8* %m
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chk:
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%bc = bitcast i8* %m to i32*
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%lgp = load i32*, i32** @gp, align 8, !nonnull !0
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%cmp2 = icmp eq i32* %bc, %lgp
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br i1 %cmp2, label %retst, label %chk2
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chk2:
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ret i8* %n
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; CHECK-LABEL: compare_ret_escape
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; CHECK: %cmp = icmp eq i8* %n, %c
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; CHECK: %cmp2 = icmp eq i32* %lgp, %bc
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}
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; The malloc call for %m cannot be elided since it is used in the call to function f.
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; However, the cmp can be folded to true as %n doesnt escape and %m, %n are distinct allocations
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define i1 @compare_distinct_pointer_escape() {
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%m = call i8* @malloc(i64 4)
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%n = call i8* @malloc(i64 4)
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tail call void @f() [ "deopt"(i8* %m) ]
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%cmp = icmp ne i8* %m, %n
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ret i1 %cmp
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; CHECK-LABEL: compare_distinct_pointer_escape
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; CHECK-NEXT: %m = call i8* @malloc(i64 4)
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; CHECK-NEXT: tail call void @f() [ "deopt"(i8* %m) ]
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; CHECK-NEXT: ret i1 true
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}
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!0 = !{}
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