[PATCH] D97974: [gvn] CSE gc.relocates based on meaning, not spelling

[Philip Reames via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG51b13a7ea0b9: [gvn] CSE gc.relocates based on meaning, not spelling (authored by reames).

Changed prior to commit:
  https://reviews.llvm.org/D97974?vs=328274&id=328575#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D97974/new/

https://reviews.llvm.org/D97974

Files:
  llvm/lib/Transforms/Scalar/GVN.cpp
  llvm/test/Transforms/GVN/gc_relocate.ll


Index: llvm/test/Transforms/GVN/gc_relocate.ll
===================================================================
--- llvm/test/Transforms/GVN/gc_relocate.ll
+++ llvm/test/Transforms/GVN/gc_relocate.ll
@@ -49,14 +49,10 @@
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[SAFEPOINT_TOKEN:%.*]] = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0) [ "gc-live"(i32 addrspace(1)* [[IN:%.*]], i32 addrspace(1)* [[IN]]) ]
 ; CHECK-NEXT:    [[BASE:%.*]] = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token [[SAFEPOINT_TOKEN]], i32 0, i32 0)
-; CHECK-NEXT:    [[DERIVED:%.*]] = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token [[SAFEPOINT_TOKEN]], i32 0, i32 1)
-; CHECK-NEXT:    [[SAFEPOINT_TOKEN2:%.*]] = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0) [ "gc-live"(i32 addrspace(1)* [[BASE]], i32 addrspace(1)* [[DERIVED]]) ]
+; CHECK-NEXT:    [[SAFEPOINT_TOKEN2:%.*]] = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0) [ "gc-live"(i32 addrspace(1)* [[BASE]], i32 addrspace(1)* [[BASE]]) ]
 ; CHECK-NEXT:    [[BASE_RELOC:%.*]] = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token [[SAFEPOINT_TOKEN2]], i32 0, i32 0)
-; CHECK-NEXT:    [[DERIVED_RELOC:%.*]] = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token [[SAFEPOINT_TOKEN2]], i32 0, i32 1)
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 addrspace(1)* [[BASE_RELOC]], null
-; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32 addrspace(1)* [[DERIVED_RELOC]], null
-; CHECK-NEXT:    [[CMP:%.*]] = and i1 [[CMP1]], [[CMP2]]
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 [[CMP1]]
 ;
 entry:
   %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0) ["gc-live"(i32 addrspace(1)* %in, i32 addrspace(1)* %in)]
Index: llvm/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVN.cpp
+++ llvm/lib/Transforms/Scalar/GVN.cpp
@@ -62,6 +62,7 @@
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/Statepoint.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Use.h"
 #include "llvm/IR/Value.h"
@@ -289,8 +290,17 @@
   Expression e;
   e.type = I->getType();
   e.opcode = I->getOpcode();
-  for (Use &Op : I->operands())
-    e.varargs.push_back(lookupOrAdd(Op));
+  if (const GCRelocateInst *GCR = dyn_cast<GCRelocateInst>(I)) {
+    // gc.relocate is 'special' call: its second and third operands are
+    // not real values, but indices into statepoint's argument list.
+    // Use the refered to values for purposes of identity.
+    e.varargs.push_back(lookupOrAdd(GCR->getOperand(0)));
+    e.varargs.push_back(lookupOrAdd(GCR->getBasePtr()));
+    e.varargs.push_back(lookupOrAdd(GCR->getDerivedPtr()));
+  } else {
+    for (Use &Op : I->operands())
+      e.varargs.push_back(lookupOrAdd(Op));
+  }
   if (I->isCommutative()) {
     // Ensure that commutative instructions that only differ by a permutation
     // of their operands get the same value number by sorting the operand value


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