[llvm] a161268 - [InstCombine] Add test for freeze of GEP with recurrence offset (NFC) (#145541)
via llvm-commits
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Thu Jun 26 01:51:53 PDT 2025
Author: Cullen Rhodes
Date: 2025-06-26T09:51:50+01:00
New Revision: a16126844750a04faec6ee49f90227a8013ca2a7
URL: https://github.com/llvm/llvm-project/commit/a16126844750a04faec6ee49f90227a8013ca2a7
DIFF: https://github.com/llvm/llvm-project/commit/a16126844750a04faec6ee49f90227a8013ca2a7.diff
LOG: [InstCombine] Add test for freeze of GEP with recurrence offset (NFC) (#145541)
The freeze should be pushed through the GEP to the ptr like in:
https://godbolt.org/z/jrcozT8rz
Added:
Modified:
llvm/test/Transforms/InstCombine/freeze.ll
Removed:
################################################################################
diff --git a/llvm/test/Transforms/InstCombine/freeze.ll b/llvm/test/Transforms/InstCombine/freeze.ll
index 8875ce1c566f3..9733f1b732c3f 100644
--- a/llvm/test/Transforms/InstCombine/freeze.ll
+++ b/llvm/test/Transforms/InstCombine/freeze.ll
@@ -877,6 +877,104 @@ exit: ; preds = %loop
ret void
}
+; The recurrence for the GEP offset can't produce poison so the freeze should
+; be pushed through to the ptr, but this is not currently supported.
+define void @fold_phi_gep_phi_offset(ptr %init, ptr %end, i64 noundef %n) {
+; CHECK-LABEL: @fold_phi_gep_phi_offset(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[I:%.*]] = phi ptr [ [[INIT:%.*]], [[ENTRY:%.*]] ], [ [[I_NEXT_FR:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF:%.*]] = phi i64 [ [[N:%.*]], [[ENTRY]] ], [ [[OFF_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF_NEXT]] = shl i64 [[OFF]], 3
+; CHECK-NEXT: [[I_NEXT:%.*]] = getelementptr i8, ptr [[I]], i64 [[OFF_NEXT]]
+; CHECK-NEXT: [[I_NEXT_FR]] = freeze ptr [[I_NEXT]]
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr [[I_NEXT_FR]], [[END:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop: ; preds = %loop, %entry
+ %i = phi ptr [ %init, %entry ], [ %i.next.fr, %loop ]
+ %off = phi i64 [ %n, %entry ], [ %off.next, %loop ]
+ %off.next = shl i64 %off, 3
+ %i.next = getelementptr i8, ptr %i, i64 %off.next
+ %i.next.fr = freeze ptr %i.next
+ %cond = icmp eq ptr %i.next.fr, %end
+ br i1 %cond, label %loop, label %exit
+
+exit: ; preds = %loop
+ ret void
+}
+
+; Offset is still guaranteed not to be poison, so the freeze could be moved
+; here if we strip inbounds from the GEP, but this is not currently supported.
+define void @fold_phi_gep_inbounds_phi_offset(ptr %init, ptr %end, i64 noundef %n) {
+; CHECK-LABEL: @fold_phi_gep_inbounds_phi_offset(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[I:%.*]] = phi ptr [ [[INIT:%.*]], [[ENTRY:%.*]] ], [ [[I_NEXT_FR:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF:%.*]] = phi i64 [ [[N:%.*]], [[ENTRY]] ], [ [[OFF_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF_NEXT]] = shl i64 [[OFF]], 3
+; CHECK-NEXT: [[I_NEXT:%.*]] = getelementptr inbounds i8, ptr [[I]], i64 [[OFF_NEXT]]
+; CHECK-NEXT: [[I_NEXT_FR]] = freeze ptr [[I_NEXT]]
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr [[I_NEXT_FR]], [[END:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop: ; preds = %loop, %entry
+ %i = phi ptr [ %init, %entry ], [ %i.next.fr, %loop ]
+ %off = phi i64 [ %n, %entry ], [ %off.next, %loop ]
+ %off.next = shl i64 %off, 3
+ %i.next = getelementptr inbounds i8, ptr %i, i64 %off.next
+ %i.next.fr = freeze ptr %i.next
+ %cond = icmp eq ptr %i.next.fr, %end
+ br i1 %cond, label %loop, label %exit
+
+exit: ; preds = %loop
+ ret void
+}
+
+; GEP can produce poison, check freeze isn't moved.
+define void @cant_fold_phi_gep_phi_offset(ptr %init, ptr %end, i64 %n) {
+; CHECK-LABEL: @cant_fold_phi_gep_phi_offset(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[I:%.*]] = phi ptr [ [[INIT:%.*]], [[ENTRY:%.*]] ], [ [[I_NEXT_FR:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF:%.*]] = phi i64 [ [[N:%.*]], [[ENTRY]] ], [ [[OFF_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[OFF_NEXT]] = shl i64 [[OFF]], 3
+; CHECK-NEXT: [[I_NEXT:%.*]] = getelementptr inbounds i8, ptr [[I]], i64 [[OFF_NEXT]]
+; CHECK-NEXT: [[I_NEXT_FR]] = freeze ptr [[I_NEXT]]
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr [[I_NEXT_FR]], [[END:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop: ; preds = %loop, %entry
+ %i = phi ptr [ %init, %entry ], [ %i.next.fr, %loop ]
+ %off = phi i64 [ %n, %entry ], [ %off.next, %loop ]
+ %off.next = shl i64 %off, 3
+ %i.next = getelementptr inbounds i8, ptr %i, i64 %off.next
+ %i.next.fr = freeze ptr %i.next
+ %cond = icmp eq ptr %i.next.fr, %end
+ br i1 %cond, label %loop, label %exit
+
+exit: ; preds = %loop
+ ret void
+}
+
define void @fold_phi_multiple_insts(i32 %init, i32 %n) {
; CHECK-LABEL: @fold_phi_multiple_insts(
; CHECK-NEXT: entry:
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