From d74de3ce79d4ab3495650bfcc4682cab09514b89 Mon Sep 17 00:00:00 2001 From: "Jayanth Krishnamurthy jayanth.krishnamurthy@ibm.com" Date: Mon, 15 Sep 2025 17:33:42 -0500 Subject: cmd/compile: improve uint8/uint16 logical immediates on PPC64 Logical ops on uint8/uint16 (AND/OR/XOR) with constants sometimes materialized the mask via MOVD (often as a negative immediate), even when the value fit in the UI-immediate range. This prevented the backend from selecting andi. / ori / xori forms. This CL makes: UI-immediate truncation is performed only at the use-site of logical-immediate ops, and only when the constant does not fit in the 8- or 16-bit unsigned domain (m != uint8(m) / m != uint16(m)). This avoids negative-mask materialization and enables correct emission of UI-form logical instructions. Arithmetic SI-immediate instructions (addi, subfic, etc.) and other use-patterns are unchanged. Codegen tests are added to ensure the expected andi./ori/xori patterns appear and that MOVD is not emitted for valid 8/16-bit masks. Change-Id: I9fcdf4498c4e984c7587814fb9019a75865c4a0d Cq-Include-Trybots: luci.golang.try:gotip-linux-ppc64_power10,gotip-linux-ppc64_power8,gotip-linux-ppc64le_power8,gotip-linux-ppc64le_power9,gotip-linux-ppc64le_power10 Reviewed-on: https://go-review.googlesource.com/c/go/+/704015 LUCI-TryBot-Result: Go LUCI Reviewed-by: Paul Murphy Reviewed-by: Cherry Mui Reviewed-by: Mark Freeman --- src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules | 3 --- 1 file changed, 3 deletions(-) (limited to 'src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules') diff --git a/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules b/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules index 15e6f72519..cd60e79a9d 100644 --- a/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules +++ b/src/cmd/compile/internal/ssa/_gen/PPC64latelower.rules @@ -18,9 +18,6 @@ (SETBC [1] cmp) && buildcfg.GOPPC64 <= 9 => (ISELZ [1] (MOVDconst [1]) cmp) (SETBCR [1] cmp) && buildcfg.GOPPC64 <= 9 => (ISELZ [5] (MOVDconst [1]) cmp) -// The upper bits of the smaller than register values is undefined. Take advantage of that. -(AND x:(MOVDconst [m]) n) && t.Size() <= 2 => (ANDconst [int64(int16(m))] n) - // Convert simple bit masks to an equivalent rldic[lr] if possible. (AND x:(MOVDconst [m]) n) && isPPC64ValidShiftMask(m) => (RLDICL [encodePPC64RotateMask(0,m,64)] n) (AND x:(MOVDconst [m]) n) && m != 0 && isPPC64ValidShiftMask(^m) => (RLDICR [encodePPC64RotateMask(0,m,64)] n) -- cgit v1.3-6-g1900