[llvm] 37374fb - [InstCombine] Simplify nonnull phi nodes (#128466)
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Sat Mar 1 07:11:59 PST 2025
Author: Yingwei Zheng
Date: 2025-03-01T23:11:55+08:00
New Revision: 37374fbcd33c6b96637d0d6195e269a46f0daa04
URL: https://github.com/llvm/llvm-project/commit/37374fbcd33c6b96637d0d6195e269a46f0daa04
DIFF: https://github.com/llvm/llvm-project/commit/37374fbcd33c6b96637d0d6195e269a46f0daa04.diff
LOG: [InstCombine] Simplify nonnull phi nodes (#128466)
Fix some regressions caused by
https://github.com/llvm/llvm-project/pull/128111.
Compile-time impact:
https://llvm-compile-time-tracker.com/compare.php?from=1e0e4169dd00bf8a37cef8d74d0add7861982c4e&to=3a27268e264826ef9cf493f645507e490f05e7f3&stat=instructions%3Au
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
llvm/test/Transforms/InstCombine/load.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 221511e9aba0b..c1f5e286ab3ed 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -1011,6 +1011,21 @@ Value *InstCombinerImpl::simplifyNonNullOperand(Value *V,
}
}
+ if (auto *PHI = dyn_cast<PHINode>(V)) {
+ bool Changed = false;
+ for (Use &U : PHI->incoming_values()) {
+ // We set Depth to RecursionLimit to avoid expensive recursion.
+ if (auto *Res = simplifyNonNullOperand(U.get(), HasDereferenceable,
+ RecursionLimit)) {
+ replaceUse(U, Res);
+ Changed = true;
+ }
+ }
+ if (Changed)
+ addToWorklist(PHI);
+ return nullptr;
+ }
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/load.ll b/llvm/test/Transforms/InstCombine/load.ll
index d10aabff6709a..736a31fc6ae0a 100644
--- a/llvm/test/Transforms/InstCombine/load.ll
+++ b/llvm/test/Transforms/InstCombine/load.ll
@@ -481,3 +481,30 @@ define i16 @load_select_with_null_gep3(i1 %cond, ptr %p, i64 %x, i64 %y) {
%res = load i16, ptr %gep2, align 2
ret i16 %res
}
+
+define i32 @test_load_phi_with_select(ptr %p, i1 %cond1) {
+; CHECK-LABEL: @test_load_phi_with_select(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP_BODY:%.*]]
+; CHECK: loop.body:
+; CHECK-NEXT: [[TARGET:%.*]] = getelementptr inbounds nuw i8, ptr [[BASE:%.*]], i64 24
+; CHECK-NEXT: [[LOAD:%.*]] = load i32, ptr [[TARGET]], align 4
+; CHECK-NEXT: [[COND21:%.*]] = icmp eq i32 [[LOAD]], 0
+; CHECK-NEXT: br i1 [[COND21]], label [[LOOP_BODY]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret i32 [[LOAD]]
+;
+entry:
+ br label %loop.body
+
+loop.body:
+ %base = phi ptr [ %p, %entry ], [ %sel, %loop.body ]
+ %target = getelementptr inbounds i8, ptr %base, i64 24
+ %load = load i32, ptr %target, align 4
+ %sel = select i1 %cond1, ptr null, ptr %p
+ %cond2 = icmp eq i32 %load, 0
+ br i1 %cond2, label %loop.body, label %exit
+
+exit:
+ ret i32 %load
+}
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