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3828d43959
Factor out the reachability such that multiple queries to find reachability of values are fast. This is based on finding the ANTIC points in the CFG which do not change during hoisting. The ANTIC points are basically the dominance-frontiers in the inverse graph. So we introduce a data structure (CHI nodes) to keep track of values flowing out of a basic block. We only do this for values with multiple occurrences in the function as they are the potential hoistable candidates. This patch allows us to hoist instructions to a basic block with >2 successors, as well as deal with infinite loops in a trivial way. Relevant test cases are added to show the functionality as well as regression fixes from PR32821. Regression from previous GVNHoist: We do not hoist fully redundant expressions because fully redundant expressions are already handled by NewGVN Differential Revision: https://reviews.llvm.org/D35918 Reviewers: dberlin, sebpop, gberry, llvm-svn: 313116
78 lines
2.7 KiB
LLVM
78 lines
2.7 KiB
LLVM
; RUN: opt -gvn-hoist -newgvn -gvn-hoist -S < %s | FileCheck %s
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; Test to demonstrate that newgvn creates opportunities for
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; more gvn-hoist when sibling branches contain identical expressions.
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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; Check that all "or" expressions are hoisted.
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; CHECK-LABEL: @encode
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; CHECK: or i32
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; CHECK-NOT: or i32
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define i8* @encode(i8* %p, i32 %v) {
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entry:
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%p.addr = alloca i8*, align 8
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%v.addr = alloca i32, align 4
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store i8* %p, i8** %p.addr, align 8
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store i32 %v, i32* %v.addr, align 4
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%0 = load i32, i32* %v.addr, align 4
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%cmp = icmp ult i32 %0, 23
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br i1 %cmp, label %if.then, label %if.else
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if.then: ; preds = %entry
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%1 = load i32, i32* %v.addr, align 4
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%or = or i32 %1, 128
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%conv = trunc i32 %or to i8
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%2 = load i8*, i8** %p.addr, align 8
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%incdec.ptr = getelementptr inbounds i8, i8* %2, i32 1
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store i8* %incdec.ptr, i8** %p.addr, align 8
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store i8 %conv, i8* %2, align 1
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br label %if.end15
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if.else: ; preds = %entry
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%3 = load i32, i32* %v.addr, align 4
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%cmp1 = icmp ult i32 %3, 42
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br i1 %cmp1, label %if.then3, label %if.else9
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if.then3: ; preds = %if.else
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%4 = load i32, i32* %v.addr, align 4
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%or4 = or i32 %4, 128
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%conv5 = trunc i32 %or4 to i8
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%5 = load i8*, i8** %p.addr, align 8
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%incdec.ptr6 = getelementptr inbounds i8, i8* %5, i32 1
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store i8* %incdec.ptr6, i8** %p.addr, align 8
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store i8 %conv5, i8* %5, align 1
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%6 = load i32, i32* %v.addr, align 4
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%conv7 = trunc i32 %6 to i8
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%7 = load i8*, i8** %p.addr, align 8
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%incdec.ptr8 = getelementptr inbounds i8, i8* %7, i32 1
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store i8* %incdec.ptr8, i8** %p.addr, align 8
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store i8 %conv7, i8* %7, align 1
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br label %if.end
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if.else9: ; preds = %if.else
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%8 = load i32, i32* %v.addr, align 4
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%or10 = or i32 %8, 128
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%conv11 = trunc i32 %or10 to i8
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%9 = load i8*, i8** %p.addr, align 8
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%incdec.ptr12 = getelementptr inbounds i8, i8* %9, i32 1
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store i8* %incdec.ptr12, i8** %p.addr, align 8
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store i8 %conv11, i8* %9, align 1
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%10 = load i32, i32* %v.addr, align 4
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%shr = lshr i32 %10, 7
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%conv13 = trunc i32 %shr to i8
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%11 = load i8*, i8** %p.addr, align 8
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%incdec.ptr14 = getelementptr inbounds i8, i8* %11, i32 1
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store i8* %incdec.ptr14, i8** %p.addr, align 8
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store i8 %conv13, i8* %11, align 1
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br label %if.end
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if.end: ; preds = %if.else9, %if.then3
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br label %if.end15
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if.end15: ; preds = %if.end, %if.then
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%12 = load i8*, i8** %p.addr, align 8
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ret i8* %12
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}
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