8310524: C2: record parser-generated LoadN nodes for IGVN

Reviewed-by: chagedorn, rcastanedalo, thartmann
This commit is contained in:
Daniel Lundén 2023-12-08 11:04:39 +00:00 committed by Roberto Castañeda Lozano
parent bad5edf146
commit 9e48b90c7f
2 changed files with 68 additions and 0 deletions
src/hotspot/share/opto
test/hotspot/jtreg/compiler/c2/irTests/igvn

@ -1563,6 +1563,11 @@ Node* GraphKit::make_load(Node* ctl, Node* adr, const Type* t, BasicType bt,
if (((bt == T_OBJECT) && C->do_escape_analysis()) || C->eliminate_boxing()) {
// Improve graph before escape analysis and boxing elimination.
record_for_igvn(ld);
if (ld->is_DecodeN()) {
// Also record the actual load (LoadN) in case ld is DecodeN
assert(ld->in(1)->Opcode() == Op_LoadN, "Assumption invalid: input to DecodeN is not LoadN");
record_for_igvn(ld->in(1));
}
}
return ld;
}

@ -0,0 +1,63 @@
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package compiler.c2.irTests.igvn;
import compiler.lib.ir_framework.*;
/*
* @test
* @bug 8310524
* @summary Test that IGVN optimizes away one of two identical LoadNs.
* @library /test/lib /
* @run driver compiler.c2.irTests.igvn.TestLoadNIdeal
*/
public class TestLoadNIdeal {
public static void main(String[] args) {
// Ensure that we run with compressed oops
TestFramework.runWithFlags("-XX:+UseCompressedOops");
}
static class A { int x; }
@DontInline
void dummy(A p[]) { }
@Test
@IR(applyIf = { "UseCompressedOops", "true" }, counts = { IRNode.LOAD_N, "1" })
int test() {
A p[] = new A[1];
p[0] = new A();
// The dummy method is not inlined => Escape analysis
// cannot ensure that p[0] is unmodified after the call.
dummy(p);
// We should only need to load p[0] once here. Storing A within an
// array adds range checks for the first load and ensures the second
// load is not optimized already at bytecode parsing.
return p[0].x + p[0].x;
}
}