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llvm-mirror/test/Other/cgscc-libcall-update.ll
Chandler Carruth b6378546b8 [PM/LCG] Follow-up fix to r308088 to handle deletion of library
functions.

In the prior commit, we provide ordering to the LCG between functions
and library function definitions that they might begin to call through
transformations. But we still would delete these library functions from
the call graph if they became dead during inlining.

While this immediately crashed, it also exposed a loss of information.
We shouldn't remove definitions of library functions that can still
usefully participate in the LCG-powered CGSCC optimization process. If
new call edges are formed, we want to have definitions to be called.

We can still remove these functions if truly dead using global-dce, etc,
but removing them during the CGSCC walk is premature.

This fixes a crash in the new PM when optimizing some unusual libraries
that end up with "internal" lib functions such as the code in the "R"
language's libraries.

llvm-svn: 308417
2017-07-19 04:12:25 +00:00

62 lines
2.0 KiB
LLVM

; Make sure that the CGSCC pass manager can handle when instcombine simplifies
; one libcall into an unrelated libcall and update the call graph accordingly.
;
; Also check that it can handle inlining *removing* a libcall entirely.
;
; RUN: opt -passes='cgscc(inline,function(instcombine))' -S < %s | FileCheck %s
define i8* @wibble(i8* %arg1, i8* %arg2) {
; CHECK-LABEL: define i8* @wibble(
bb:
%tmp = alloca [1024 x i8], align 16
%tmp2 = getelementptr inbounds [1024 x i8], [1024 x i8]* %tmp, i64 0, i64 0
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* %arg1, i64 1024, i32 0, i1 false)
; CHECK: call void @llvm.memcpy
%tmp3 = call i64 @llvm.objectsize.i64.p0i8(i8* %tmp2, i1 false, i1 true)
%tmp4 = call i8* @__strncpy_chk(i8* %arg2, i8* %tmp2, i64 1023, i64 %tmp3)
; CHECK-NOT: call
; CHECK: call i8* @strncpy(i8* %arg2, i8* %tmp2, i64 1023)
; CHECK-NOT: call
ret i8* %tmp4
; CHECK: ret
}
define i8* @strncpy(i8* %arg1, i8* %arg2, i64 %size) noinline {
bb:
%result = call i8* @my_special_strncpy(i8* %arg1, i8* %arg2, i64 %size)
ret i8* %result
}
declare i8* @my_special_strncpy(i8* %arg1, i8* %arg2, i64 %size)
declare i64 @llvm.objectsize.i64.p0i8(i8*, i1, i1)
declare i8* @__strncpy_chk(i8*, i8*, i64, i64)
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1)
; Check that even when we completely remove a libcall we don't get the call
; graph wrong once we handle libcalls in the call graph specially to address
; the above case.
define i32 @hoge(i32* %arg1) {
; CHECK-LABEL: define i32 @hoge(
bb:
%tmp41 = load i32*, i32** null
%tmp6 = load i32, i32* %arg1
%tmp7 = call i32 @ntohl(i32 %tmp6)
; CHECK-NOT: call i32 @ntohl
ret i32 %tmp7
; CHECK: ret i32
}
; Even though this function is not used, it should be retained as it may be
; used when doing further libcall transformations.
define internal i32 @ntohl(i32 %x) {
; CHECK-LABEL: define internal i32 @ntohl(
entry:
%and2 = lshr i32 %x, 8
%shr = and i32 %and2, 65280
ret i32 %shr
}