================
@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=indvars -S | FileCheck %s
+
+declare void @foo(i16 noundef)
+
+; Function Attrs: mustprogress noreturn uwtable
+define void @bar(i64 noundef %ptr) {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = trunc i64 [[PTR:%.*]] to i4
+; CHECK-NEXT: [[TMP1:%.*]] = zext i4 [[TMP0]] to i16
+; CHECK-NEXT: br label [[WHILE_BODY:%.*]]
+; CHECK: while.body:
+; CHECK-NEXT: tail call void @foo(i16 noundef signext [[TMP1]])
+; CHECK-NEXT: br label [[WHILE_BODY]]
+;
+entry:
+ br label %while.body
+
+while.body: ; preds = %entry, %while.body
+ %0 = phi i64 [ %ptr, %entry ], [ %add.ptr, %while.body ]
+ %1 = trunc i64 %0 to i16
+ %and = and i16 %1, 15 ; loop invariant
+ tail call void @foo(i16 noundef signext %and)
----------------
markoshorro wrote:
Having something like:
`declare void @foo(i2 noundef)
entry:
%ptr.addr.0 = ptrtoint ptr %ptr to i64
br label %while.body
while.body: ; preds = %entry, %while.body
%0 = phi i64 [ %ptr.addr.0, %entry ], [ %add.ptr, %while.body ]
%1 = trunc i64 %0 to i2
%and = and i2 %1, 15 ; loop invariant
tail call void @foo(i2 noundef signext %and)
%add.ptr = add nsw i64 %0, 16
br label %while.body
}`
With this change, the IR generated is the following:
`declare void @foo(i2 noundef)
define void @bar(ptr noundef %ptr) {
entry:
%ptr.addr.0 = ptrtoint ptr %ptr to i64
%0 = trunc i64 %ptr.addr.0 to i2
br label %while.body
while.body: ; preds = %while.body, %entry
%and = and i2 %0, -1
tail call void @foo(i2 noundef signext %and)
br label %while.body
}`
This is valid to me, when you say that `trunc` can affect the result, do you
have any example in mind? Thanks!
https://github.com/llvm/llvm-project/pull/71072
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