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8237945: CTW: C2 compilation fails with assert(just_allocated_object(…

…alloc_ctl) == ptr) failed: most recent allo

Removing too strong assertion about array allocation in LibraryCallKit::tightly_coupled_allocation().

Reviewed-by: thartmann, neliasso
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Christian Hagedorn
Christian Hagedorn committed Feb 13, 2020
1 parent 8bdb972 commit e2829b7b8798faf575dec742636e3b509ec94c2f
@@ -4852,8 +4852,6 @@ LibraryCallKit::tightly_coupled_allocation(Node* ptr,

// This arraycopy must unconditionally follow the allocation of the ptr.
Node* alloc_ctl = ptr->in(0);
assert(just_allocated_object(alloc_ctl) == ptr, "most recent allo");

Node* ctl = control();
while (ctl != alloc_ctl) {
// There may be guards which feed into the slow_region.
@@ -0,0 +1,58 @@
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/*
* @test
* @bug 8237945
* @summary Test that triggers the too strong assertion "just_allocated_object(alloc_ctl) == ptr" in LibraryCallKit::tightly_coupled_allocation()
*
* @run main/othervm -Xbatch compiler.arraycopy.TestTightlyCoupledAllocationAssert
*/

package compiler.arraycopy;

public class TestTightlyCoupledAllocationAssert {

static A a;
static byte[] bArr = new byte[8];

public static void main(String[] strArr) {
for (int i = 0; i < 10000; i++ ) {
test(i % 20);
}
}

public static void test(int i) {
byte [] bArrLocal = new byte[8]; // (1)
if (i < 16) {
a = new A(); // (2)
return;
}
// The assertion "just_allocated_object(alloc_ctl) == ptr" in LibraryCallKit::tightly_coupled_allocation() fails during parsing here since
// the most recent allocation is (2) and not (1). The earlier bailout checks about the memory state (involving the variable "rawmem") pass
// because the if branch returns and the memory state from (2) is not merged with the memory state from (1) for the array copy.
System.arraycopy(bArr, 0, bArrLocal, 0, 8);
}
}

class A { }

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