[DAGCombiner] Fold [us]itofp of truncate #149391
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@llvm/pr-subscribers-backend-nvptx @llvm/pr-subscribers-llvm-selectiondag Author: Alex MacLean (AlexMaclean) ChangesFull diff: https://github.com/llvm/llvm-project/pull/149391.diff 3 Files Affected:
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 40464e91f9efc..39b46240e6c71 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -18727,6 +18727,13 @@ SDValue DAGCombiner::visitSINT_TO_FP(SDNode *N) {
if (SDValue FTrunc = foldFPToIntToFP(N, DL, DAG, TLI))
return FTrunc;
+
+ // fold (sint_to_fp (trunc nsw x)) -> (sint_to_fp x)
+ if (N0.getOpcode() == ISD::TRUNCATE && N0->getFlags().hasNoSignedWrap() &&
+ TLI.isTypeDesirableForOp(ISD::SINT_TO_FP,
+ N0.getOperand(0).getValueType()))
+ return DAG.getNode(ISD::SINT_TO_FP, DL, VT, N0.getOperand(0));
+
return SDValue();
}
@@ -18764,6 +18771,13 @@ SDValue DAGCombiner::visitUINT_TO_FP(SDNode *N) {
if (SDValue FTrunc = foldFPToIntToFP(N, DL, DAG, TLI))
return FTrunc;
+
+ // fold (uint_to_fp (trunc nuw x)) -> (uint_to_fp x)
+ if (N0.getOpcode() == ISD::TRUNCATE && N0->getFlags().hasNoUnsignedWrap() &&
+ TLI.isTypeDesirableForOp(ISD::UINT_TO_FP,
+ N0.getOperand(0).getValueType()))
+ return DAG.getNode(ISD::UINT_TO_FP, DL, VT, N0.getOperand(0));
+
return SDValue();
}
diff --git a/llvm/test/CodeGen/NVPTX/i8x4-instructions.ll b/llvm/test/CodeGen/NVPTX/i8x4-instructions.ll
index cbc9f700b1f01..aba20e6b0f27f 100644
--- a/llvm/test/CodeGen/NVPTX/i8x4-instructions.ll
+++ b/llvm/test/CodeGen/NVPTX/i8x4-instructions.ll
@@ -2311,4 +2311,51 @@ entry:
ret void
}
+define <4 x float> @test_uitofp_v4i8(<4 x i8> %a) {
+; CHECK-LABEL: test_uitofp_v4i8(
+; CHECK: {
+; CHECK-NEXT: .reg .b32 %r<10>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [test_uitofp_v4i8_param_0];
+; CHECK-NEXT: prmt.b32 %r2, %r1, 0, 0x7773U;
+; CHECK-NEXT: cvt.rn.f32.u32 %r3, %r2;
+; CHECK-NEXT: prmt.b32 %r4, %r1, 0, 0x7772U;
+; CHECK-NEXT: cvt.rn.f32.u32 %r5, %r4;
+; CHECK-NEXT: prmt.b32 %r6, %r1, 0, 0x7771U;
+; CHECK-NEXT: cvt.rn.f32.u32 %r7, %r6;
+; CHECK-NEXT: prmt.b32 %r8, %r1, 0, 0x7770U;
+; CHECK-NEXT: cvt.rn.f32.u32 %r9, %r8;
+; CHECK-NEXT: st.param.v4.b32 [func_retval0], {%r9, %r7, %r5, %r3};
+; CHECK-NEXT: ret;
+ %r = uitofp <4 x i8> %a to <4 x float>
+ ret <4 x float> %r
+}
+
+define <4 x float> @test_sitofp_v4i8(<4 x i8> %a) {
+; CHECK-LABEL: test_sitofp_v4i8(
+; CHECK: {
+; CHECK-NEXT: .reg .b16 %rs<5>;
+; CHECK-NEXT: .reg .b32 %r<10>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [test_sitofp_v4i8_param_0];
+; CHECK-NEXT: prmt.b32 %r2, %r1, 0, 0xbbb3U;
+; CHECK-NEXT: cvt.u16.u32 %rs1, %r2;
+; CHECK-NEXT: cvt.rn.f32.s16 %r3, %rs1;
+; CHECK-NEXT: prmt.b32 %r4, %r1, 0, 0xaaa2U;
+; CHECK-NEXT: cvt.u16.u32 %rs2, %r4;
+; CHECK-NEXT: cvt.rn.f32.s16 %r5, %rs2;
+; CHECK-NEXT: prmt.b32 %r6, %r1, 0, 0x9991U;
+; CHECK-NEXT: cvt.u16.u32 %rs3, %r6;
+; CHECK-NEXT: cvt.rn.f32.s16 %r7, %rs3;
+; CHECK-NEXT: prmt.b32 %r8, %r1, 0, 0x8880U;
+; CHECK-NEXT: cvt.u16.u32 %rs4, %r8;
+; CHECK-NEXT: cvt.rn.f32.s16 %r9, %rs4;
+; CHECK-NEXT: st.param.v4.b32 [func_retval0], {%r9, %r7, %r5, %r3};
+; CHECK-NEXT: ret;
+ %r = sitofp <4 x i8> %a to <4 x float>
+ ret <4 x float> %r
+}
+
attributes #0 = { nounwind }
diff --git a/llvm/test/CodeGen/NVPTX/trunc-tofp.ll b/llvm/test/CodeGen/NVPTX/trunc-tofp.ll
new file mode 100644
index 0000000000000..404c423cc026a
--- /dev/null
+++ b/llvm/test/CodeGen/NVPTX/trunc-tofp.ll
@@ -0,0 +1,81 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mcpu=sm_80 | FileCheck %s
+; RUN: %if ptxas %{ llc < %s -mcpu=sm_80 | %ptxas-verify %}
+
+target triple = "nvptx64-nvidia-cuda"
+
+define float @uitofp_trunc_nuw(i32 %x, i32 %y) {
+; CHECK-LABEL: uitofp_trunc_nuw(
+; CHECK: {
+; CHECK-NEXT: .reg .b32 %r<5>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [uitofp_trunc_nuw_param_0];
+; CHECK-NEXT: ld.param.b32 %r2, [uitofp_trunc_nuw_param_1];
+; CHECK-NEXT: add.s32 %r3, %r1, %r2;
+; CHECK-NEXT: cvt.rn.f32.u32 %r4, %r3;
+; CHECK-NEXT: st.param.b32 [func_retval0], %r4;
+; CHECK-NEXT: ret;
+ %v = add i32 %x, %y
+ %t = trunc nuw i32 %v to i16
+ %f = uitofp i16 %t to float
+ ret float %f
+}
+
+define float @sitofp_trunc_nsw(i32 %x, i32 %y) {
+; CHECK-LABEL: sitofp_trunc_nsw(
+; CHECK: {
+; CHECK-NEXT: .reg .b32 %r<5>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [sitofp_trunc_nsw_param_0];
+; CHECK-NEXT: ld.param.b32 %r2, [sitofp_trunc_nsw_param_1];
+; CHECK-NEXT: add.s32 %r3, %r1, %r2;
+; CHECK-NEXT: cvt.rn.f32.s32 %r4, %r3;
+; CHECK-NEXT: st.param.b32 [func_retval0], %r4;
+; CHECK-NEXT: ret;
+ %v = add i32 %x, %y
+ %t = trunc nsw i32 %v to i16
+ %f = sitofp i16 %t to float
+ ret float %f
+}
+
+define float @uitofp_trunc_nsw(i32 %x, i32 %y) {
+; CHECK-LABEL: uitofp_trunc_nsw(
+; CHECK: {
+; CHECK-NEXT: .reg .b16 %rs<2>;
+; CHECK-NEXT: .reg .b32 %r<5>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [uitofp_trunc_nsw_param_0];
+; CHECK-NEXT: ld.param.b32 %r2, [uitofp_trunc_nsw_param_1];
+; CHECK-NEXT: add.s32 %r3, %r1, %r2;
+; CHECK-NEXT: cvt.u16.u32 %rs1, %r3;
+; CHECK-NEXT: cvt.rn.f32.u16 %r4, %rs1;
+; CHECK-NEXT: st.param.b32 [func_retval0], %r4;
+; CHECK-NEXT: ret;
+ %v = add i32 %x, %y
+ %t = trunc nsw i32 %v to i16
+ %f = uitofp i16 %t to float
+ ret float %f
+}
+
+define float @sitofp_trunc_nuw(i32 %x, i32 %y) {
+; CHECK-LABEL: sitofp_trunc_nuw(
+; CHECK: {
+; CHECK-NEXT: .reg .b16 %rs<2>;
+; CHECK-NEXT: .reg .b32 %r<5>;
+; CHECK-EMPTY:
+; CHECK-NEXT: // %bb.0:
+; CHECK-NEXT: ld.param.b32 %r1, [sitofp_trunc_nuw_param_0];
+; CHECK-NEXT: ld.param.b32 %r2, [sitofp_trunc_nuw_param_1];
+; CHECK-NEXT: add.s32 %r3, %r1, %r2;
+; CHECK-NEXT: cvt.u16.u32 %rs1, %r3;
+; CHECK-NEXT: cvt.rn.f32.s16 %r4, %rs1;
+; CHECK-NEXT: st.param.b32 [func_retval0], %r4;
+; CHECK-NEXT: ret;
+ %v = add i32 %x, %y
+ %t = trunc nuw i32 %v to i16
+ %f = sitofp i16 %t to float
+ ret float %f
+}
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Artem-B
approved these changes
Jul 17, 2025
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/160/builds/21409 Here is the relevant piece of the build log for the reference |
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/180/builds/21552 Here is the relevant piece of the build log for the reference |
This was referenced Jul 23, 2025
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