diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 8 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/narrow-switch.ll | 68 |
2 files changed, 66 insertions, 10 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index fd64cc58a1d..3e72b1da779 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -2510,9 +2510,11 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { unsigned NewWidth = Known.getBitWidth() - std::max(LeadingKnownZeros, LeadingKnownOnes); // Shrink the condition operand if the new type is smaller than the old type. - // This may produce a non-standard type for the switch, but that's ok because - // the backend should extend back to a legal type for the target. - if (NewWidth > 0 && NewWidth < Known.getBitWidth()) { + // But do not shrink to a non-standard type, because backend can't generate + // good code for that yet. + // TODO: We can make it agressive again after fixing PR39569. + if (NewWidth > 0 && NewWidth < Known.getBitWidth() && + shouldChangeType(Known.getBitWidth(), NewWidth)) { IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth); Builder.SetInsertPoint(&SI); Value *NewCond = Builder.CreateTrunc(Cond, Ty, "trunc"); diff --git a/llvm/test/Transforms/InstCombine/narrow-switch.ll b/llvm/test/Transforms/InstCombine/narrow-switch.ll index 474bd820c8f..a8fa3e528db 100644 --- a/llvm/test/Transforms/InstCombine/narrow-switch.ll +++ b/llvm/test/Transforms/InstCombine/narrow-switch.ll @@ -3,9 +3,6 @@ ; RUN: opt < %s -instcombine -S -data-layout=n32 | FileCheck %s --check-prefix=ALL --check-prefix=CHECK32 ; RUN: opt < %s -instcombine -S -data-layout=n32:64 | FileCheck %s --check-prefix=ALL --check-prefix=CHECK64 -; In all cases, the data-layout is irrelevant. We should shrink as much as possible in InstCombine -; and allow the backend to expand as much as needed to ensure optimal codegen for any target. - define i32 @positive1(i64 %a) { ; ALL-LABEL: @positive1( ; ALL: switch i32 @@ -102,13 +99,19 @@ return: ; Make sure to avoid assertion crashes and use the type before ; truncation to generate the sub constant expressions that leads ; to the recomputed condition. +; We allow to truncate from i64 to i59 if in 32-bit mode, +; because both are illegal. define void @trunc64to59(i64 %a) { ; ALL-LABEL: @trunc64to59( -; ALL: switch i59 -; ALL-NEXT: i59 0, label %sw.bb1 -; ALL-NEXT: i59 18717182647723699, label %sw.bb2 -; ALL-NEXT: ] +; ALL-CHECK32: switch i59 +; ALL-CHECK32-NEXT: i59 0, label %sw.bb1 +; ALL-CHECK32-NEXT: i59 18717182647723699, label %sw.bb2 +; ALL-CHECK32-NEXT: ] +; ALL-CHECK64: switch i64 +; ALL-CHECK64-NEXT: i64 0, label %sw.bb1 +; ALL-CHECK64-NEXT: i64 18717182647723699, label %sw.bb2 +; ALL-CHECK64-NEXT: ] ; entry: %tmp0 = and i64 %a, 15 @@ -206,3 +209,54 @@ return: ; preds = %sw.epilog, %sw.bb2, ret i32 %rval } +; https://llvm.org/bugs/show_bug.cgi?id=29009 + +@a = global i32 0, align 4 +@njob = global i32 0, align 4 + +declare i32 @goo() + +; Make sure we do not shrink to illegal types (i3 in this case) +; if original type is legal (i32 in this case) + +define void @PR29009() { +; ALL-LABEL: @PR29009( +; ALL: switch i32 +; ALL-NEXT: i32 0, label +; ALL-NEXT: i32 3, label +; ALL-NEXT: ] +; + br label %1 + +; <label>:1: ; preds = %10, %0 + %2 = load volatile i32, i32* @njob, align 4 + %3 = icmp ne i32 %2, 0 + br i1 %3, label %4, label %11 + +; <label>:4: ; preds = %1 + %5 = call i32 @goo() + %6 = and i32 %5, 7 + switch i32 %6, label %7 [ + i32 0, label %8 + i32 3, label %9 + ] + +; <label>:7: ; preds = %4 + store i32 6, i32* @a, align 4 + br label %10 + +; <label>:8: ; preds = %4 + store i32 1, i32* @a, align 4 + br label %10 + +; <label>:9: ; preds = %4 + store i32 2, i32* @a, align 4 + br label %10 + +; <label>:10: ; preds = %13, %12, %11, %10, %9, %8, %7 + br label %1 + +; <label>:11: ; preds = %1 + ret void +} + |
