[llvm] [ValueTracking] isNonZero trunc of sub of ptr2int's with recursive GEP where pointers are limited to a 32bit alloc. (PR #84933)

[Yingwei Zheng via llvm-commits]

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@@ -25,6 +26,11 @@ using namespace PatternMatch;
 
 #define DEBUG_TYPE "instcombine"
 
+// Controls the maximum memory allocation to 32-bit or 4GB.
+static cl::opt<bool> PointerAllocationsLimitedto32bit(
+    "alloc-limit-32bit", cl::init(false),
+    cl::desc("A Pointer with max 32bit allocs"));
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dtcxzyw wrote:

I agree.
WARNING: Adding this flag may violate SPEC's rule.
See also https://www.spec.org/cpu2017/Docs/runrules.html#rule_1.4 and https://www.spec.org/cpu2017/results/res2023q1/cpu2017-20221223-33220.html.


https://github.com/llvm/llvm-project/pull/84933