[VPlan][LV] Fix invalid truncation in VPScalarIVStepsRecipe #137832
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Replace CreateTrunc with CreateSExtOrTrunc in VPScalarIVStepsRecipe to safely handle type conversion. This prevents assertion failures from invalid truncation when StartIdx0 has a smaller integer type than IntStepTy. The assertion was introduced by commit 783a846.
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@llvm/pr-subscribers-backend-powerpc @llvm/pr-subscribers-llvm-transforms Author: Maryam Moghadas (maryammo) ChangesReplace CreateTrunc with CreateSExtOrTrunc in VPScalarIVStepsRecipe to safely handle type conversion. This prevents assertion failures from invalid truncation when StartIdx0 has a smaller integer type than IntStepTy. The assertion was introduced by commit 783a846. Full diff: https://github.com/llvm/llvm-project/pull/137832.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 75d056026025a..6ca43eec63dd4 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -2134,7 +2134,7 @@ void VPScalarIVStepsRecipe::execute(VPTransformState &State) {
Builder.CreateMul(StartIdx0, ConstantInt::get(StartIdx0->getType(),
getUnrollPart(*this)));
}
- StartIdx0 = Builder.CreateTrunc(StartIdx0, IntStepTy);
+ StartIdx0 = Builder.CreateSExtOrTrunc(StartIdx0, IntStepTy);
}
if (!FirstLaneOnly && State.VF.isScalable()) {
diff --git a/llvm/test/Transforms/LoopVectorize/PowerPC/vplan-scalarivsext-crash.ll b/llvm/test/Transforms/LoopVectorize/PowerPC/vplan-scalarivsext-crash.ll
new file mode 100644
index 0000000000000..66b54a29b913c
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/PowerPC/vplan-scalarivsext-crash.ll
@@ -0,0 +1,31 @@
+; RUN: opt -passes=loop-vectorize -S < %s > /dev/null
+; REQUIRES: asserts
+
+target datalayout = "E-m:a-p:32:32-Fi32-i64:64-n32"
+target triple = "powerpc-ibm-aix7.2.0.0"
+
+define void @__power_mod_NMOD_power_init(ptr %a, ptr %b, i32 %n) {
+entry:
+ br label %loop_entry
+
+loop_exit: ; preds = %loop_header
+ br label %loop_entry
+
+loop_entry: ; preds = %loop_exit, %entry
+ %sum.0 = phi double [ 0.000000e+00, %entry ], [ %sum.1, %loop_exit ]
+ %x = load double, ptr %a, align 8
+ br label %loop_header
+
+loop_header: ; preds = %loop_body, %loop_entry
+ %sum.1 = phi double [ %sum.0, %loop_entry ], [ %sum.next, %loop_body ]
+ %i = phi i32 [ 0, %loop_entry ], [ %i.next, %loop_body ]
+ %cond = icmp sgt i32 %i, %n
+ br i1 %cond, label %loop_exit, label %loop_body
+
+loop_body: ; preds = %loop_header
+ store double %sum.1, ptr %b, align 8
+ %sum.next = fadd reassoc double %sum.1, %x
+ %i.next = add i32 %i, 1
+ br label %loop_header
+}
+
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lukel97
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Apr 29, 2025
llvm/test/Transforms/LoopVectorize/PowerPC/vplan-scalarivsext-crash.ll
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fhahn
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Apr 29, 2025
| @@ -0,0 +1,31 @@ | |||
| ; RUN: opt -passes=loop-vectorize -disable-output -S < %s | |||
| ; REQUIRES: asserts | |||
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Please update the test to check the output as @lukel97 suggested, we should check we get the expected result. You then can also remove REQUIRES: asserts
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| loop_exit: ; preds = %loop_header | ||
| br label %loop_entry | ||
|
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||
| loop_entry: ; preds = %loop_exit, %entry | ||
| %sum.0 = phi double [ 0.000000e+00, %entry ], [ %sum.1, %loop_exit ] | ||
| %x = load double, ptr %a, align 8 | ||
| br label %loop_header |
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Do we need the loop nest or can this simply be a single loop?
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I updated the test to use a single loop.
fhahn
approved these changes
May 5, 2025
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| ;. | ||
| ; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]} | ||
| ; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1} | ||
| ; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"} | ||
| ; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]]} | ||
| ;. |
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can use --check-globals=none to remove those uninteresting checks
GeorgeARM
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to GeorgeARM/llvm-project
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May 7, 2025
) Replace CreateTrunc with CreateSExtOrTrunc in VPScalarIVStepsRecipe to safely handle type conversion. This prevents assertion failures from invalid truncation when StartIdx0 has a smaller integer type than IntStepTy. The assertion was introduced by commit 783a846. Fixes llvm#137185
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Replace CreateTrunc with CreateSExtOrTrunc in VPScalarIVStepsRecipe to safely handle type conversion. This prevents assertion failures from invalid truncation when StartIdx0 has a smaller integer type than IntStepTy. The assertion was introduced by commit 783a846.
Fixes #137185