aa15ea47e2
It actually implements support for seeing through loads, using alias analysis to refine the result. This is rather limited, but I didn't want to rely on more than available analysis at that point (to be gentle with compilation time), and it does seem to catch common scenario, as showcased by the included tests. Differential Revision: https://reviews.llvm.org/D122431
46 lines
1.6 KiB
LLVM
46 lines
1.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt --instcombine -lower-constant-intrinsics -S < %s | FileCheck %s
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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declare i64 @llvm.objectsize.i64.p0i8(i8*, i1 immarg, i1 immarg, i1 immarg)
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define dso_local i64 @check_store_load(i1 %cond) local_unnamed_addr {
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; CHECK-LABEL: @check_store_load(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PTR01:%.*]] = alloca [10 x i8], align 1
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; CHECK-NEXT: br i1 [[COND:%.*]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
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; CHECK: if.then:
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; CHECK-NEXT: [[PTR01_SUB:%.*]] = getelementptr inbounds [10 x i8], [10 x i8]* [[PTR01]], i64 0, i64 0
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; CHECK-NEXT: br label [[RETURN:%.*]]
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; CHECK: if.end:
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; CHECK-NEXT: [[PTR12:%.*]] = alloca [12 x i8], align 1
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; CHECK-NEXT: [[PTR12_SUB:%.*]] = getelementptr inbounds [12 x i8], [12 x i8]* [[PTR12]], i64 0, i64 0
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; CHECK-NEXT: br label [[RETURN]]
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; CHECK: return:
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; CHECK-NEXT: [[STOREMERGE:%.*]] = phi i8* [ [[PTR12_SUB]], [[IF_END]] ], [ [[PTR01_SUB]], [[IF_THEN]] ]
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; CHECK-NEXT: ret i64 12
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;
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entry:
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%holder = alloca i8*
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%ptr0 = alloca i8, i64 10
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br i1 %cond, label %if.then, label %if.end
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if.then:
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store i8* %ptr0, i8** %holder
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br label %return
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if.end:
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%ptr1 = alloca i8, i64 12
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store i8* %ptr1, i8** %holder
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br label %return
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return:
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%held = load i8*, i8** %holder
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%objsize = call i64 @llvm.objectsize.i64.p0i8(i8* %held, i1 false, i1 true, i1 false)
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ret i64 %objsize
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}
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