mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-09-09 15:57:28 +00:00
637582eaf7
turning a code like this: if (foo) free(foo) into that: free(foo) Move a call to free from basic block FB into FB's predecessor, P, when the path from P to FB is taken only if the argument of free is not equal to NULL. Some restrictions apply on P and FB to be sure that this code motion is profitable. Namely: 1. FB must have only one predecessor P. 2. FB must contain only the call to free plus an unconditional branch to S. 3. P's successors are FB and S. Because of 1., we will not increase the code size when moving the call to free from FB to P. Because of 2., FB will be empty after the move. Because of 2. and 3., P's branch instruction becomes useless, so as FB (simplifycfg will do the job). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171762 91177308-0d34-0410-b5e6-96231b3b80d8
123 lines
4.1 KiB
LLVM
123 lines
4.1 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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; PR1201
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define i32 @main(i32 %argc, i8** %argv) {
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; CHECK: @main
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%c_19 = alloca i8*
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%malloc_206 = tail call i8* @malloc(i32 mul (i32 ptrtoint (i8* getelementptr (i8* null, i32 1) to i32), i32 10))
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store i8* %malloc_206, i8** %c_19
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%tmp_207 = load i8** %c_19
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tail call void @free(i8* %tmp_207)
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ret i32 0
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; CHECK-NEXT: ret i32 0
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}
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declare noalias i8* @calloc(i32, i32) nounwind
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declare noalias i8* @malloc(i32)
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declare void @free(i8*)
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define i1 @foo() {
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; CHECK: @foo
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; CHECK-NEXT: ret i1 false
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%m = call i8* @malloc(i32 1)
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%z = icmp eq i8* %m, null
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call void @free(i8* %m)
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ret i1 %z
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}
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declare void @llvm.lifetime.start(i64, i8*)
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declare void @llvm.lifetime.end(i64, i8*)
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declare i64 @llvm.objectsize.i64(i8*, i1)
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declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
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declare void @llvm.memmove.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
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declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i32, i1) nounwind
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define void @test3(i8* %src) {
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; CHECK: @test3
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; CHECK-NEXT: ret void
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%a = call noalias i8* @malloc(i32 10)
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call void @llvm.lifetime.start(i64 10, i8* %a)
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call void @llvm.lifetime.end(i64 10, i8* %a)
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%size = call i64 @llvm.objectsize.i64(i8* %a, i1 true)
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store i8 42, i8* %a
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %src, i32 32, i32 1, i1 false)
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call void @llvm.memmove.p0i8.p0i8.i32(i8* %a, i8* %src, i32 32, i32 1, i1 false)
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call void @llvm.memset.p0i8.i32(i8* %a, i8 5, i32 32, i32 1, i1 false)
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%alloc2 = call noalias i8* @calloc(i32 5, i32 7) nounwind
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%z = icmp ne i8* %alloc2, null
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ret void
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}
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;; This used to crash.
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define void @test4() {
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; CHECK: @test4
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; CHECK-NEXT: ret void
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%A = call i8* @malloc(i32 16000)
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%B = bitcast i8* %A to double*
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%C = bitcast double* %B to i8*
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call void @free(i8* %C)
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ret void
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}
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; CHECK: @test5
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define void @test5(i8* %ptr, i8** %esc) {
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call i8* @malloc
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; CHECK-NEXT: call void @llvm.memcpy
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; CHECK-NEXT: call void @llvm.memmove
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; CHECK-NEXT: store
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; CHECK-NEXT: call void @llvm.memcpy
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; CHECK-NEXT: call void @llvm.memmove
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; CHECK-NEXT: call void @llvm.memset
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; CHECK-NEXT: store volatile
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; CHECK-NEXT: ret
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%a = call i8* @malloc(i32 700)
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%b = call i8* @malloc(i32 700)
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%c = call i8* @malloc(i32 700)
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%d = call i8* @malloc(i32 700)
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%e = call i8* @malloc(i32 700)
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%f = call i8* @malloc(i32 700)
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%g = call i8* @malloc(i32 700)
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* %ptr, i8* %a, i32 32, i32 1, i1 false)
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call void @llvm.memmove.p0i8.p0i8.i32(i8* %ptr, i8* %b, i32 32, i32 1, i1 false)
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store i8* %c, i8** %esc
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* %d, i8* %ptr, i32 32, i32 1, i1 true)
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call void @llvm.memmove.p0i8.p0i8.i32(i8* %e, i8* %ptr, i32 32, i32 1, i1 true)
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call void @llvm.memset.p0i8.i32(i8* %f, i8 5, i32 32, i32 1, i1 true)
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store volatile i8 4, i8* %g
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ret void
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}
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;; When a basic block contains only a call to free and this block is accessed
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;; through a test of the argument of free against null, move the call in the
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;; predecessor block.
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;; Using simplifycfg will remove the empty basic block and the branch operation
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;; Then, performing a dead elimination will remove the comparison.
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;; This is what happens with -O1 and upper.
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; CHECK: @test6
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define void @test6(i8* %foo) minsize {
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; CHECK: %tobool = icmp eq i8* %foo, null
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;; Call to free moved
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; CHECK-NEXT: tail call void @free(i8* %foo)
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; CHECK-NEXT: br i1 %tobool, label %if.end, label %if.then
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; CHECK: if.then:
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;; Block is now empty and may be simplified by simplifycfg
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; CHECK-NEXT: br label %if.end
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; CHECK: if.end:
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; CHECK-NEXT: ret void
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entry:
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%tobool = icmp eq i8* %foo, null
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br i1 %tobool, label %if.end, label %if.then
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if.then: ; preds = %entry
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tail call void @free(i8* %foo)
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br label %if.end
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if.end: ; preds = %entry, %if.then
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ret void
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}
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