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25d9f1156f
Summary: Previously, when allocating unspillable live ranges, we would never attempt to split. We would always bail out and try last ditch graph recoloring. This patch changes this by attempting to split all live intervals before performing recoloring. This fixes LLVM bug PR14879. I can't add test cases for any backends other than AVR because none of them have small enough register classes to trigger the bug. Reviewers: qcolombet Subscribers: MatzeB Differential Revision: https://reviews.llvm.org/D25070 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283838 91177308-0d34-0410-b5e6-96231b3b80d8
79 lines
2.4 KiB
LLVM
79 lines
2.4 KiB
LLVM
; RUN: llc < %s -march=avr | FileCheck %s
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; This tests how LLVM handles IR which puts very high
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; presure on the PTRREGS class for the register allocator.
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;
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; This causes a problem because we only have one small register
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; class for loading and storing from pointers - 'PTRREGS'.
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; One of these registers is also used for the frame pointer, meaning
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; that we only ever have two registers available for these operations.
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;
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; There is an existing bug filed for this issue - PR14879.
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;
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; The specific failure:
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; LLVM ERROR: ran out of registers during register allocation
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;
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; It has been assembled from the following c code:
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;
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; struct ss
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; {
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; int a;
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; int b;
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; int c;
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; };
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;
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; void loop(struct ss *x, struct ss **y, int z)
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; {
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; int i;
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; for (i=0; i<z; ++i)
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; {
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; x->c += y[i]->b;
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; }
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; }
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%struct.ss = type { i16, i16, i16 }
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; CHECK-LABEL: loop
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define void @loop(%struct.ss* %x, %struct.ss** %y, i16 %z) #0 {
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entry:
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%x.addr = alloca %struct.ss*, align 2
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%y.addr = alloca %struct.ss**, align 2
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%z.addr = alloca i16, align 2
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%i = alloca i16, align 2
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store %struct.ss* %x, %struct.ss** %x.addr, align 2
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store %struct.ss** %y, %struct.ss*** %y.addr, align 2
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store i16 %z, i16* %z.addr, align 2
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store i16 0, i16* %i, align 2
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br label %for.cond
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for.cond: ; preds = %for.inc, %entry
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%tmp = load i16, i16* %i, align 2
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%tmp1 = load i16, i16* %z.addr, align 2
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%cmp = icmp slt i16 %tmp, %tmp1
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br i1 %cmp, label %for.body, label %for.end
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for.body: ; preds = %for.cond
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%tmp2 = load %struct.ss**, %struct.ss*** %y.addr, align 2
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%tmp3 = load i16, i16* %i, align 2
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%arrayidx = getelementptr inbounds %struct.ss*, %struct.ss** %tmp2, i16 %tmp3
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%tmp4 = load %struct.ss*, %struct.ss** %arrayidx, align 2
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%b = getelementptr inbounds %struct.ss, %struct.ss* %tmp4, i32 0, i32 1
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%tmp5 = load i16, i16* %b, align 2
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%tmp6 = load %struct.ss*, %struct.ss** %x.addr, align 2
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%c = getelementptr inbounds %struct.ss, %struct.ss* %tmp6, i32 0, i32 2
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%tmp7 = load i16, i16* %c, align 2
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%add = add nsw i16 %tmp7, %tmp5
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store i16 %add, i16* %c, align 2
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br label %for.inc
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for.inc: ; preds = %for.body
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%tmp8 = load i16, i16* %i, align 2
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%inc = add nsw i16 %tmp8, 1
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store i16 %inc, i16* %i, align 2
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br label %for.cond
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for.end: ; preds = %for.cond
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ret void
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}
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