[PATCH] D126952: [DAGCombiner] Remove overzealous assertion when folding assert+trunc+assert (PR55846)
Nikita Popov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 7 00:50:35 PDT 2022
This revision was automatically updated to reflect the committed changes.
nikic marked an inline comment as done.
Closed by commit rG5a64bc207ee0: [DAGCombiner] Remove overzealous assertion when folding assert+trunc+assert… (authored by nikic).
Changed prior to commit:
https://reviews.llvm.org/D126952?vs=433986&id=434716#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D126952/new/
https://reviews.llvm.org/D126952
Files:
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/test/CodeGen/X86/pr55846.ll
Index: llvm/test/CodeGen/X86/pr55846.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/pr55846.ll
@@ -0,0 +1,26 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+; After legalization, this could be: "i8 truncate (i64 AssertZext X, Type: i9)"
+; The AssertZext does not add information, so it should be eliminated,
+; but that must not trigger a compile-time assert.
+
+define void @test(i64* %p) {
+; CHECK-LABEL: test:
+; CHECK: # %bb.0:
+; CHECK-NEXT: movl $256, %eax # imm = 0x100
+; CHECK-NEXT: movq %rax, (%rdi)
+; CHECK-NEXT: retq
+ %sel = select i1 true, i64 256, i64 0
+ br label %bb2
+
+bb2:
+ store i64 %sel, i64* %p, align 4
+ %p.bc = bitcast i64* %p to <2 x i1>*
+ %load = load <2 x i1>, <2 x i1>* %p.bc, align 1
+ br label %bb3
+
+bb3:
+ %use = add <2 x i1> %load, zeroinitializer
+ ret void
+}
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12508,13 +12508,9 @@
// This eliminates the later assert:
// assert (trunc (assert X, i8) to iN), i1 --> trunc (assert X, i1) to iN
// assert (trunc (assert X, i1) to iN), i8 --> trunc (assert X, i1) to iN
+ SDLoc DL(N);
SDValue BigA = N0.getOperand(0);
EVT BigA_AssertVT = cast<VTSDNode>(BigA.getOperand(1))->getVT();
- assert(BigA_AssertVT.bitsLE(N0.getValueType()) &&
- "Asserting zero/sign-extended bits to a type larger than the "
- "truncated destination does not provide information");
-
- SDLoc DL(N);
EVT MinAssertVT = AssertVT.bitsLT(BigA_AssertVT) ? AssertVT : BigA_AssertVT;
SDValue MinAssertVTVal = DAG.getValueType(MinAssertVT);
SDValue NewAssert = DAG.getNode(Opcode, DL, BigA.getValueType(),
@@ -12530,10 +12526,6 @@
Opcode == ISD::AssertZext) {
SDValue BigA = N0.getOperand(0);
EVT BigA_AssertVT = cast<VTSDNode>(BigA.getOperand(1))->getVT();
- assert(BigA_AssertVT.bitsLE(N0.getValueType()) &&
- "Asserting zero/sign-extended bits to a type larger than the "
- "truncated destination does not provide information");
-
if (AssertVT.bitsLT(BigA_AssertVT)) {
SDLoc DL(N);
SDValue NewAssert = DAG.getNode(Opcode, DL, BigA.getValueType(),
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