[llvm] [DAGCombine] Propagate truncate to operands (PR #98666)

[Matt Arsenault via llvm-commits]

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@@ -5,9 +5,9 @@ define i16 @num_sign_bits_mul_i48_0(i8 %X, i8 %Y, i8 %Z, i8 %W) {
 ; GFX9-LABEL: num_sign_bits_mul_i48_0:
 ; GFX9:       ; %bb.0:
 ; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX9-NEXT:    v_mul_i32_i24_sdwa v0, sext(v0), sext(v1) dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:BYTE_0 src1_sel:BYTE_0
-; GFX9-NEXT:    v_mul_i32_i24_sdwa v1, sext(v2), sext(v3) dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:BYTE_0 src1_sel:BYTE_0
-; GFX9-NEXT:    v_mul_i32_i24_e32 v0, v0, v1
+; GFX9-NEXT:    v_mul_lo_u16_sdwa v2, sext(v2), sext(v3) dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:BYTE_0 src1_sel:BYTE_0
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arsenm wrote:

Better 

https://github.com/llvm/llvm-project/pull/98666