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llvm-project/llvm/test/Transforms/GVN/calloc-load-removal.ll

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GVN: Enable value forwarding for calloc Enable value forwarding for loads from `calloc()` without an intervening store. This change extends GVN to handle the following case: %1 = tail call noalias i8* @calloc(i64 1, i64 4) %2 = bitcast i8* %1 to i32* ; This load is trivially constant zero %3 = load i32* %2, align 4 This is analogous to the handling for `malloc()` in the same places. `malloc()` returns `undef`; `calloc()` returns a zero value. Note that it is correct to return zero even for out of bounds GEPs since the result of such a GEP would be undefined. Patch by Philip Reames! llvm-svn: 210828
2014-06-13 05:16:19 +08:00
; RUN: opt -S -basicaa -gvn < %s | FileCheck %s
; RUN: opt -S -basicaa -gvn -disable-simplify-libcalls < %s | FileCheck %s -check-prefix=CHECK_NO_LIBCALLS
; Check that loads from calloc are recognized as being zero.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
; Function Attrs: nounwind uwtable
define i32 @test1() {
%1 = tail call noalias i8* @calloc(i64 1, i64 4)
%2 = bitcast i8* %1 to i32*
; This load is trivially constant zero
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
%3 = load i32, i32* %2, align 4
GVN: Enable value forwarding for calloc Enable value forwarding for loads from `calloc()` without an intervening store. This change extends GVN to handle the following case: %1 = tail call noalias i8* @calloc(i64 1, i64 4) %2 = bitcast i8* %1 to i32* ; This load is trivially constant zero %3 = load i32* %2, align 4 This is analogous to the handling for `malloc()` in the same places. `malloc()` returns `undef`; `calloc()` returns a zero value. Note that it is correct to return zero even for out of bounds GEPs since the result of such a GEP would be undefined. Patch by Philip Reames! llvm-svn: 210828
2014-06-13 05:16:19 +08:00
ret i32 %3
; CHECK-LABEL: @test1(
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
; CHECK-NOT: %3 = load i32, i32* %2, align 4
GVN: Enable value forwarding for calloc Enable value forwarding for loads from `calloc()` without an intervening store. This change extends GVN to handle the following case: %1 = tail call noalias i8* @calloc(i64 1, i64 4) %2 = bitcast i8* %1 to i32* ; This load is trivially constant zero %3 = load i32* %2, align 4 This is analogous to the handling for `malloc()` in the same places. `malloc()` returns `undef`; `calloc()` returns a zero value. Note that it is correct to return zero even for out of bounds GEPs since the result of such a GEP would be undefined. Patch by Philip Reames! llvm-svn: 210828
2014-06-13 05:16:19 +08:00
; CHECK: ret i32 0
; CHECK_NO_LIBCALLS-LABEL: @test1(
; CHECK_NO_LIBCALLS: load
; CHECK_NO_LIBCALLS: ret i32 %
}
declare noalias i8* @calloc(i64, i64)